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DDIISSSSEERRTTAATTIIOONN
zur Erlangung des akademischen Grades „Doktor der Naturwissenschaften” an der Fakultät für
Geowissenschaften, Geographie und Astronomie der Universität Wien:
““DDEEFFOORRMMAATTIIOONN AARROOUUNNDD BBAASSIINN SSCCAALLEE NNOORRMMAALL FFAAUULLTTSS””
VVeerrffaasssseerr
MMaagg.. DDaarrkkoo SSppaahhiićć
WWiieenn,, OOkkttoobbeerr 22001100
Studienkennzahl It Studienblatt A 091 426
Dissertationgebiet It. Studienblatt Geologie
Betreuerin/Betreuer: Prof. Dr. Bernhard Grasemann
“Оni koji žele nešto da nauče nikada nisu bili besposleni!“
("Those who have wish to learn, they never had been vacuous”)
CHARLES-LOUIS DE SECONDAT, BARON DE LA BRÈDE ET DE MONTESQUIEU (1689-1755)
TTaabbllee ooff CCoonntteennttss
DDIISSSSEERRTTAATTIIOONN.................................................................................................................................................. 11
““DDEEFFOORRMMAATTIIOONN AARROOUUNNDD BBAASSIINN SSCCAALLEE NNOORRMMAALL FFAAUULLTTSS”” .................................................. 11
11.. IINNTTRROODDUUCCTTIIOONN ..............................................................................................................................................1177
11..11 DDEEFFIINNIITTIIOONN OOFF FFAAUULLTT DDRRAAGG,, CCUURRRREENNTT SSTTAATTEE OOFF RREESSEEAARRCCHH AANNDD
MMOOTTIIVVAATTIIOONN 1188
11..22 AAIIMM AANNDD AAPPPPRROOAACCHH..........................................................................................................................1199
11..33 NNOORRMMAALL FFAAUULLTT SSYYSSTTEEMMSS -- GGEEOOMMEETTRRIICCAALL PPRROOPPEERRTTIIEESS AANNDD LLIINNKKAAGGEE
PPRROOCCEESSSSEESS 2211
11..33..11 LLIISSTTRRIICC FFAAUULLTTSS..........................................................................................................................2222
11..33..22 PPLLAANNAARR FFAAUULLTTSS OOFF FFIINNIITTEE LLEENNGGTTHH ..............................................................................2244
11..44 FFAAUULLTT GGRROOWWTTHH BBYY SSEEGGMMEENNTT LLIINNKKAAGGEE ................................................................................2266
11..55 KKEEYY QQUUEESSTTIIOONNSS AADDDDRREESSSSEEDD IINN TTHHEE TTHHEESSIISS ..................................................................2288
11..66 OOUUTTLLIINNEE OOFF TTHHEE TTHHEESSIISS ..............................................................................................................2299
22.. PPOOSSSSIIBBIILLIITTIIEESS OOFF GGRROOUUNNDD PPEENNEETTRRAATTIINNGG RRAADDAARR ((GGPPRR)) IINN SSHHAALLLLOOWW
SSUUBBSSUURRFFAACCEE 33DD SSTTRRUUCCTTUURRAALL MMOODDEELLIINNGG ((AANN EEXXAAMMPPLLEE FFRROOMM SSTT.. MMAARRGGAARREETTEENN GGRRAAVVEELL PPIITT,,
EEIISSEENNSSTTAADDTT--SSOOPPRROONN BBAASSIINN)) ........................................................................................................................................3355
22..11 IINNTTRROODDUUCCTTIIOONN....................................................................................................................................3377
22..22 RREEGGIIOONNAALL SSEETTTTIINNGG,, LLIITTHHOOLLOOGGYY AANNDD GGEEOOMMEETTRRYY OOFF SSTTRRUUCCTTUURRAALL FFEEAATTUURREESS
OOFF TTHHEE IINNVVEESSTTIIGGAATTEEDD AARREEAA........................................................................................................................................3388
22..33 GGRROOUUNNDD PPEENNEETTRRAATTIINNGG RRAADDAARR ((GGPPRR)) MMEEAASSUURREEMMEENNTTSS........................................4411
22..33..11 PPRROOCCEESSSSIINNGG SSTTEEPPSS OOFF TTHHEE 4400 AANNDD 8800 MMHHZZ GGPPRR RRAADDAAGGRRAAMMSS............4422
22..44 SSTTRRUUCCTTUURRAALL 33DD MMOODDEELL IINN GGOOCCAADD......................................................................................4433
22..55 RREESSUULLTTSS AANNDD DDIISSCCUUSSSSIIOONN ........................................................................................................4433
22..66 CCOONNCCLLUUSSIIOONN ........................................................................................................................................4455
33.. LLIISSTTRRIICC VVEERRSSUUSS PPLLAANNAARR NNOORRMMAALL FFAAUULLTT GGEEOOMMEETTRRYY:: AANN EEXXAAMMPPLLEE FFRROOMM TTHHEE
EEIISSEENNSSTTAADDTT--SSOOPPRROONN BBAASSIINN ((EE AAUUSSTTRRIIAA)) ..........................................................................................................4499
33..11 IINNTTRROODDUUCCTTIIOONN....................................................................................................................................5511
33..22 RREEGGIIOONNAALL SSEETTTTIINNGG ..........................................................................................................................5522
33..33 DDAATTAA AACCQQUUIISSIITTIIOONN,, PPRROOCCEESSSSIINNGG AANNDD RREESSUULLTTSS ........................................................5544
33..33..11 SSTTRRUUCCTTUURRAALL DDAATTAA ..................................................................................................................5566
33..33..22 GGRROOUUNNDD PPEENNEETTRRAATTIINNGG RRAADDAARR ......................................................................................5588
33..33..33 LLAASSEERR SSCCAANN AANNDD 33DD MMOODDEELL ............................................................................................6600
33..44 DDEEPPTTHH TTOO DDEETTAACCHHMMEENNTT CCOONNSSTTRRUUCCTTIIOONN AASSSSUUMMIINNGG AA LLIISSTTRRIICC FFAAUULLTT
GGEEOOMMEETTRRYY 6622
33..55 DDIISSCCUUSSSSIIOONN..........................................................................................................................................6644
33..55..11 LLIISSTTRRIICC VVEERRSSUUSS PPLLAANNAARR FFAAUULLTT GGEEOOMMEETTRRYY ............................................................6644
33..55..22 HHYYDDRROOCCAARRBBOONN TTRRAAPPSS............................................................................................................6677
33..66 CCOONNCCLLUUSSIIOONNSS......................................................................................................................................6699
44.. IIDDEENNTTIIFFYYIINNGG FFAAUULLTT SSEEGGMMEENNTTSS FFRROOMM 33DD FFAAUULLTT DDRRAAGG AANNAALLYYSSIISS ..............................7777
44..11 IINNTTRROODDUUCCTTIIOONN....................................................................................................................................7799
44..22 GGEEOOLLOOGGIICCAALL SSEETTTTIINNGG ....................................................................................................................8800
44..33 SSEEIISSMMIICC DDAATTAASSEETT AANNDD AANNAALLYYTTIICCAALL MMEETTHHOODDSS ..............................................................8833
44..33..11 33DD SSEEIISSMMIICC DDAATTAA FFRROOMM TTHHEE VVIIEENNNNAA BBAASSIINN ........................................................8833
44..33..22 GGEENNEERRAATTIIOONN OOFF AA SSTTRRUUCCTTUURRAALL MMOODDEELL ....................................................................8855
44..44 GGEEOOMMEETTRRIICCAALL AANNAALLYYSSIISS OOFF FFAAUULLTT PPLLAANNEE AANNDD MMAARRKKEERR HHOORRIIZZOONNSS ................8877
44..44..11 GGEEOOMMEETTRRIICC FFEEAATTUURREESS OOFF TTHHEE FFAAUULLTT SSUURRFFAACCEE ....................................................8877
44..44..22 GGEEOOMMEETTRRIICC FFEEAATTUURREESS OOFF MMAARRKKEERR HHOORRIIZZOONNSS......................................................9922
44..44..33 IINNTTEERRPPRREETTAATTIIOONN OOFF FFAAUULLTT AARRCCHHIITTEECCTTUURREE ............................................................9977
44..55 DDIISSCCUUSSSSIIOONN..........................................................................................................................................9988
44..55..11 FFAAUULLTT DDIISSPPLLAACCEEMMEENNTT AANNDD MMOORRPPHHOOLLOOGGYY AASS CCRRIITTEERRIIOONNSS FFOORR
SSEEGGMMEENNTTEEDD FFAAUULLTTSS ....................................................................................................................................................9988
44..55..22 FFAAUULLTT DDRRAAGG AASS AA CCRRIITTEERRIIOONN TTOO IIDDEENNTTIIFFYY FFAAUULLTT SSEEGGMMEENNTTSS ................ 110011
44..55..33 EEVVOOLLUUTTIIOONN OOFF TTHHEE MMAARRKKGGRRAAFFNNEEUUSSIIEEDDLL FFAAUULLTT.............................................. 110044
44..55..44 FFOOOOTTWWAALLLL GGEEOOMMEETTRRYY PPRREEDDIICCTTIIOONN .......................................................................... 110077
44..66 CCOONNCCLLUUSSIIOONNSS.................................................................................................................................. 110099
55.. SSYYNNTTHHEESSIISS:: IIMMPPOORRTTAANNCCEE OOFF FFAAUULLTT DDRRAAGG CCRRIITTEERRIIOONN IINN AASSSSEESSSSMMEENNTT OOFF FFAAUULLTT
SSUURRFFAACCEE GGEEOOMMEETTRRYY AANNDD SSEEGGMMEENNTTEEDD PPAATTTTEERRNN.............................................................................................. 111199
55..11 GGEENNEERRAALL CCOONNCCLLUUSSIIOONNSS............................................................................................................ 112200
55..11..11 SSIIGGNNIIFFIICCAANNCCEE OOFF 33DD SSTTRRUUCCTTUURRAALL MMOODDEELLIINNGG ................................................ 112200
55..11..22 RREEVVEERRSSEE FFAAUULLTT DDRRAAGG AANNDD GGEEOOMMEETTRRIICCAALL FFAAUULLTT MMOODDEELLSS ........................ 112211
55..11..33 FFAAUULLTT DDRRAAGG AASS CCRRIITTEERRIIOONN TTOO RREECCOOGGNNIIZZEE FFAAUULLTT SSEEGGMMEENNTTSS................ 112222
55..11..44 PPRROOGGRREESSSSIIVVEE EEVVOOLLUUTTIIOONN OOFF SSEEGGMMEENNTTEEDD FFAAUULLTTSS RREECCOONNSSTTRRUUCCTTEEDD BBYY
FFAAUULLTT DDRRAAGG AAMMPPLLIITTUUDDEE CCRRIITTEERRIIOONN ............................................................................................................ 112233
55..22 PPRREESSEENNTTEEDD SSOOLLUUTTIIOONNSS AANNDD FFUUTTUURREE OOUUTTLLOOOOKK........................................................ 112244
55..22..11 NNUUMMEERRIICCAALL MMOODDEELLIINNGG OOFF PPRROOPPAAGGAATTIINNGG SSEEGGMMEENNTTSS AANNDD AASSSSOOCCIIAATTEEDD
FFAAUULLTT DDRRAAGG 112244
55..22..22 PPRREEDDIICCTTIINNGG PPOOSSSSIIBBLLEE WWEEAAKK ZZOONNEESS NNEEAARR FFAAUULLTTSS IINN HHYYDDRROOCCAARRBBOONN
RREESSEERRVVOOIIRRSS 112255
66.. AAPPPPEENNDDIIXX 11 .................................................................................................................................................. 113311
Deformation around basin scale normal faults
7
Abstract
Faults in the earth crust occur within large range of scales from micro-
scale over mesoscopic to large basin scale faults. Frequently deformation
associated with faulting is not only limited to the fault plane alone, but
rather forms a combination with continuous near field deformation in the
wall rock, a phenomenon that is generally called fault drag.
The correct interpretation and recognition of fault drag is fundamental
for the reconstruction of the fault history and determination of fault
kinematics, as well as prediction in areas of limited exposure or beyond
comprehensive seismic resolution. Based on fault analyses derived from 3D
visualization of natural examples of fault drag, the importance of fault
geometry for the deformation of marker horizons around faults is
investigated. The complex 3D structural models presented here are based on
a combination of geophysical datasets and geological fieldwork.
On an outcrop scale example of fault drag in the hanging wall of a
normal fault, located at St. Margarethen, Burgenland, Austria, data from
Ground Penetrating Radar (GPR) measurements, detailed mapping and
terrestrial laser scanning were used to construct a high-resolution structural
model of the fault plane, the deformed marker horizons and associated
secondary faults. In order to obtain geometrical information about the
largely unexposed master fault surface, a standard listric balancing dip
domain technique was employed. The results indicate that for this normal
fault a listric shape can be excluded, as the constructed fault has a
geologically meaningless shape cutting upsection into the sedimentary
strata. This kinematic modeling result is additionally supported by the
observation of deformed horizons in the footwall of the structure.
Alternatively, a planar fault model with reverse drag of markers in the
hanging wall and footwall is proposed.
Deformation around basin scale normal faults
8
A second part of this thesis investigates a large scale normal fault in
the central Vienna Basin from commercial 3D seismic data. In addition to
detailed conventional fault analysis (displacement and fault shape), syn-and
anticlinal structures of sedimentary horizons occurring both in hanging wall
and footwall are assessed. Reverse drag geometries of variable magnitudes
are found to correlate with local displacement maxima along the fault. In
contrast, normal drag is observed along segment boundaries and relay
zones. Thus, the detailed documentation of the distribution, type and
magnitude of fault drag provides additional information on the fault
evolution, as initial fault segments as well as linkage or relay zones can be
identified.
Deformation around basin scale normal faults
9
Zusammenfassung
In der Erdkruste treten Störungen über einen großen Bereich von
mikro- über makroskopisch bis zu weitläufigen Störungen in großen Becken
auf. Häufig ist die Deformation im Zusammenhang mit Störungen nicht nur
auf die Störungsfläche selbst begrenzt, sondern ist vielmehr eine
Kombination mit kontinuierlichen Verbiegung des Gesteins in der
Störungsumgebung. Dieses Phänomen wird als fault drag bezeichnet.
Die korrekte Interpretation und Erkennung von fault drag ist
wesentlich für die Rekonstruierung der Störungsgeschichte, für die
Bestimmung der Störungskinematik und für die Störungsprognose in
schlecht aufgeschlossenen Gebieten oder bei unzureichender
Seismikauflösung.
Der Einfluss der Störungsgeometrie auf die Deformation von
Markerhorizonten in der Umgebung von Störungen basiert auf
Störungsanalysen, die durch 3D Visualisierung von natürlichen Beispielen
von fault drag untersucht wurden. Die komplexen strukturellen Modelle, die
in dieser Arbeit untersucht worden sind, beruhen auf einer Kombination aus
geophysikalischen Datensätzen und geologischer Feldarbeit.
Anhand eines Beispiels von fault drag im Aufschlussmaßstab im
Hangenden einer Abschiebung in St. Margarethen (Burgenland, Österreich)
konnte mit Daten von Georadarmessungen (GPR), einer ausführlichen
Kartierung und einem terrestrischen Laser Scan ein hochauflösendes
strukturelles Model der Störungsfläche, der deformierten Markerhorizonte
und den damit verbundenen sekundären Störungen konstruiert werden.
Eine Methode zur Bilanzierung von listrischen Störungen wurde zur
kinematischen Analyse angewendet, um geometrische Informationen über
die weitgehend schlecht aufgeschlossene Hauptabschiebung zu bekommen.
Die Ergebnisse zeigen, dass eine listrische Störungsgeometrie für diese
Deformation around basin scale normal faults
10
Abschiebung ausgeschlossen werden kann, da die konstruierte Störung
wieder nach oben in die überlagernden Sedimente schneidet und somit
geologisch nicht sinnvoll ist. Die Ergebnisse dieser kinematischen Analysen
werden noch zusätzlich unterstützt durch das Auftreten von deformierten
Horizonten im Liegenden der Abschiebung. Alternativ wird eine planare
Störungsgeometrie mit reverse drag von Markern im Hangenden und im
Liegenden der Abschiebung vorgeschlagen.
Der zweite Teil dieser Arbeit untersucht eine Abschiebung im großen
Maßstab im zentralen Wiener Becken anhand von kommerziellen 3D
Seismikdaten. Zusätzlich zu der konventionellen Störungsanalyse (Versatz
und Störungsform) sind syn- und antiklinale Strukturen von sedimentären
Horizonten, die im Liegenden und im Hangenden der Abschiebung zu finden
waren, kartiert worden. Es konnte gezeigt werden, dass reverse drag-
Geometrien unterschiedlich starker Magnituden mit lokalen Versatzmaxima
entlang der Störung korrelieren. Im Unterschied dazu konnte normal drag
entlang von Segmenträndern und Transferzonen nachgewiesen werden.
Daraus folgt, dass die ausführliche Dokumentation der Verteilung, die
Art und die Magnitude des fault drag zusätzliche Information über die
Störungsentstehung liefert, da sowohl initiale Störungssegmente als auch
Verbindungs- und Transferzonen identifiziert werden können.
Deformation around basin scale normal faults
11
Проширени абстракт
Раседи у Земљиној коpи се могу појавити у различитим
димензијама, од микро-, преко мезо- до великих басенских раседа.
Често деформација која се настаје синхроно са раседом није ограничена
искључиво на раседну површ, већ је то комбинација раседа и
континуиране деформације у околним стенама, који се генерално назива
Реверсни Драг (Reverse Drag).
Правилна интерпретатција и препознавање реверсног драг-а је
основа за реконструкцију постепеног развоја и историје раседне
кинематике, као за предикцију у подручијима лимитираних изданака или
подручја изван одговарајуче резулуције сеизмичких података. Базиpано
на анализи раседа изведеној на основу тродимензионалне анализе
визуализованих раседа и њихових драг-ова, важност геометрије
седимената око раседа и њихова еволуција су детаљно истраживане.
Комплексни тродимензионални структурно-геолошки модели су
базирани на комбинацији геофизичких подака и теренског геолошког
рада уз који је коришчћена најновија ласерка технологија. Сви подаци
као што су коненционалне регионално-геолошки подаци и резултати
теренског картирања (дифиталне геолошке карте, трасе раседа извучене
на ласрског фотографији – ортфото), геофизика (Георадарски снимци -
радарграми и тродимензионални сеизмички блок) као и географски
подаци (координате узете помоћу DGPS -а тј. Дигиталног Глобал
Поситионинг Система као и аероснимци) су интегрисани у Географски
Информациони Систем (GIS) и накнадно у тродимензионално
структурно-геолошке моделе.
Деформације настале близу површине анализиране су путем
комбинацијом Георадарског мерења тј снимања, теребским картирањем
Deformation around basin scale normal faults
12
која су овбавњена у близини шљункаре (тип површинског копа) која се
налази Ст.Маргаретену, Бургенланд, Аустрија. Истраживано подручје је
лоцирано у оквиру источне маргине Ајзенштат-Шопронског басена који
сам под-басен Бечког басена. У шљункари средњемиоценска сукцесија
се сатоји од слојева конгломерата, песковитих конгломерата, финозрних
пескова и алерврита варијабилне дебњине који су видњиви дуж од око
10м зида шњункаре који се пружа правцем запад – исток. Ови
неконсолидовани седименти су пресечени бројним коњугативним
раседима правца пружања север – југ који тону ка истоку без видљивог
синседиментног прираста слојева. Ови раседи смичу, повлаче и померају
ову велику седиментну сукцесију која има облик антиформе. Овакав
облик седимената указује да ова кластична сукцесија је у ствари
разкровљена повлата већег раседа регионалног значаја који је лоциран
у близини.
Да бих се добила трећа димензија картираних раседа и околних
структура, мрежа 40-то мегахерцних георадрграма је снимљена.
Радарграми су постављени паралелно и управно на картирани изданак.
Интерпретација раседних структура снимљених радарграмима, је
подпомогнута ортофотографијом која је навучена на претходно
снимљени ласерски скен изданка. Пошто су подаци са, и иза изданка
интегрисани у тродимензионални структурно-геолошки модел, да би се
добила информација о дубинској геометрији раседа, стандарним метод
„балансирања падних домена“ је коришћен.
Студија великих басенсих деформација је базирана на основу
утицаја раста сегментованог раседа на миценсе седименте централног
Бечког басена. Обострани утицај је приказан комбинацијом
тродимензионалних и кинематских параметара. Испитивани су маркер
хоризонти у повлати и подини Маркграјфнојзидл раседа, где према 3Д
сеизмичким подацима раседна површ истог је неправилног-закривљеног
облика. Након формирања коплексног 3Д модела, почетна
аистраживања су базирана на конвенцијалној анализи раседа
Deformation around basin scale normal faults
13
приказујући орјентацију, дисплејсмент и курватуру као
тродимензионалне карте. Ова три параметра су обезбедили податке о
кинематици и морфологији раседа, међутим резултати нсиу били
довољни да се реконструише еволуција раседа и дефинише шема
сегментације.
Како би се одредили старији сегменти раседа, ово истраживање се
фокусира на појаву нормалног и реверсног драг-а на маркер
хоризонтима, пре свега о домену повлате. Анализом односа између
геометрије раседне површине и раседног драг-а, формирана је метода
која допушта олакшану идентификацију индивидуалних раседних
сегмената па и фазну реконструкцију раседне еволуције.
Deformation around basin scale normal faults
14
Acknowledgements
I thank all the members of Department for Geodynamics and
Sedimentology from the University of Vienna, for support and good time
during my stay in Vienna.
Initially I would to thank members of the Structural Processes Group
for the assistance during Ground Penetrating Radar fieldwork. During field
acquisition and subsequent processing and interpretation, a significant role
was assigned to the Technical University of Vienna, particularly Dr. Michael
Behm and Dr. Alexander Haring to whom I wish to thank for the help and
guidance throughout the GPR and laser scan processing and interpretation
tasks. In addition, I would like to thank Dr. Kurt Decker, Dr. Michael
Wagreich and Dr. Mathias Harzhauser for sharing valuable information about
the St. Margareten gravel pit during the active excavation and exploitation
phase.
During my training for seismic interpretation, my thanks are directed
Dr. M. Hölzel, Mag. A. Zamolyi and Mag. A. Beidinger for Landmark
assistance. I thank OMV EP Austria for providing the 3D seismic block along
with datasets from neighboring boreholes, and appreciate discussion on the
specifics of this fault with Mag. P. Strauss and Mag. A. Beidinger. Also, I
would like to thanks Mag. Cristoph Tuitz for constructive discussions.
I own gratitude to Dr. Hugh Rice for the “native-speaker and other
geological assistance”.
I would like to express special thanks and gratitude to my supervisor
Dr. Ulrike Exner and co-supervisor Prof. Dr. Bernhard Grasemann for
guidance throughout the ‘3D fault drag world’, 3D structural modeling that
helped me to comprehend the importance of quantificational methods in
structural geology. I would like to underline their overall support, very
Deformation around basin scale normal faults
15
constructive reviews, especially detailed, careful reviews of the manuscripts
that are eventually resulted in remarkable speed of the papers acceptance.
I would like to thank to my family, who supported and encouraged me
during my years in Vienna, but also in a turbulent time before, and therefore
I would like to dedicate this PhD Thesis to them. Especially I would like to
thank to my mother, Prof. Svetlana Spahic for the overall support,
encouragement, and introduction to a magnificent 3D world through the
Plane Geometry and Perspective in Art lessons.
I dedicate my deepest gratitude for guidance and support through B.Sc
and M.Sc studies to my late mentor and friend Prof. Dr. Milun Marovic that
was tragically killed in 2009 during the geological mapping fieldwork of
Libyan Kufra Basin. Also, I own endless gratitude to my late grandmother
Prof. Trifunovic Evdokia (Daca) that during my early school time pass to me
love for Natural Sciences, Mathematics and Earth Sciences before all.
I acknowledge support from the Austrian ”Fonds zur Förderung der
wissenschaftlichen Forschung” FWF-Project P20092-N10.
Deformation around basin scale normal faults
16
Deformation around basin scale normal faults
17
1. Introduction
Deformation around basin scale normal faults
18
Faults in the Earth’s crust occur at a large range of scales from
microscopic to the scale of plate boundaries with hundreds of kilometers in
length. Frequently, deformation associated with faulting is not only
expressed by discontinuous displacement along a distinct fault surface, but
is associated with continuous deformation in the surrounding rock (Pollard &
Segall, 1987), which is expressed by folding of originally planar layers.
Following the convention of Hamblin (1965) two types of fault drag may
occur, normal and reverse drag, which are either convex (normal drag) or
concave (reverse drag) in the direction of slip along the fault. In many
investigations deflected markers with reverse drag geometry are exclusively
used as evidence for a listric fault geometry (e.g. Tearpock and Bischke,
2003), where displacement along the fault is accommodated by a rollover
anticline in the hanging wall. However, numerical and analogue studies (e.g.
Reches and Eidelman, 1995; Grasemann et al., 2003) illustrated the fact
that reverse drag forms in association with slip on planar faults of finite
extent, if the angle between the fault and the marker is roughly higher than
30°. Additionally, it was shown that reverse drag is not necessarily related
to a reactivation of a normal fault as a thrust in a compressional tectonic
regime. This alternative interpretation of fault drag has significant
implications for e.g. estimates of hydrocarbon volumes in fault-related
anticlinal structures, deformation history of regions with crustal extension,
and earthquake hazards associated with continental normal faults (e.g.
Resor, 2008).
Fault drag geometries and flanking structures have been described and
analyzed by, e.g. Barnett et al., 1987; Passchier, 2001; Exner et al. 2004;
Coelho et al. 2005; Grasemann et al. 2005 and Wiesmayr and Grasemann,
2005 on field outcrop scale or analogue and numerical modeling.
1.1 Definition of fault drag, current state of research and
motivation
Deformation around basin scale normal faults
19
Investigating the cause of host rock deformation numerous recent
publications have established that the perturbation strain generated by slip
along a distinct fault plane compensates the incompatibilities between the
background strain and the displacement along the fault by deflection of
originally planar marker layers (e.g. Passchier 2001; Grasemann et al. 2001;
Passchier et al. 2005; Grasemann et al. 2005; Exner and Dabrowski, 2010).
Following on these basic results from ideal elliptical, planar and
isolated faults and recognizing that host-rock deformation near faults is a
direct consequence of slip distribution and the mechanical interaction of
faults, this study focused on the geometrical characteristics non-planar,
irregular natural fault surafces and the associated host-rock deformation on
outcrop and basin scale. The results provided a tool that can lead to better
assessment of geometrical features, reconstruction of fault growth and
understanding of mechanical properties of propagating faults.
In order to identify natural fault drag geometries, the study was
divided in three main stages:
•• AA nnaattuurraall tthhrreeee--ddiimmeennssiioonnaall eexxaammppllee ooff ddeefflleecctteedd mmaarrkkeerrss iinn tthhee
vviicciinniittyy ooff aa nnoorrmmaall ffaauulltt aatt tthhee mmeessoo--ssccaallee wwaass aasssseesssseedd wwiitthh tthhee
aaiimm ttoo ccoonnssttrruucctt,, aa ssuurrffaaccee--ssuubbssuurrffaaccee ssttrruuccttuurraall 33DD mmooddeell..
•• BBaasseedd oonn tthhee ssttrruuccttuurraall ddaattaa ccoolllleecctteedd iinn tthhee ffiirrsstt ssttaaggee,, kkiinneemmaattiicc
bbaallaanncciinngg tteecchhnniiqquueess ((ddeepptthh--ttoo--ddeettaacchhmmeenntt rreessttoorraattiioonn,, TTeeaarrppoocckk
aanndd BBiisscchhkkee,, 22000033)) aarree eemmppllooyyeedd ttoo ccoonnssttrraaiinn tthhee ggeeoommeettrryy ooff tthhee
uunneexxppoosseedd ppaarrttss ooff tthhee ffaauulltt.. FFoorrmm tthhee rreessuullttss,, aa ppllaauussiibbllee sscceennaarriioo
ffoorr tthhee ffoorrmmaattiioonn ooff tthhee oobbsseerrvveedd ffoolldd ssttrruuccttuurreess iinn tthhee hhaannggiinngg
wwaallll aanndd ffoooottwwaallll ooff tthhee iinnvveessttiiggaatteedd nnoorrmmaall ffaauulltt iiss ddeedduucceedd..
1.2 Aim and approach
Deformation around basin scale normal faults
20
•• FFrroomm aa ccoommmmeerrcciiaall 33DD sseeiissmmiicc ddaattaasseett iinn tthhee cceennttrraall VViieennnnaa bbaassiinn,,
ddeefflleecctteedd sseeddiimmeennttaarryy hhoorriizzoonnss aaddjjaacceenntt ttoo aa mmaajjoorr nnoorrmmaall ffaauulltt
aarree mmaappppeedd iinn hhiigghh aaccccuurraaccyy.. IInn ccoommbbiinnaattiioonn wwiitthh aa ddeettaaiilleedd ffaauulltt
aannaallyyssiiss,, tthhee iinniittiiaattiioonn aanndd eevvoolluuttiioonn ooff aa llaarrggee nnoorrmmaall ffaauulltt iiss
ccoonnssttrraaiinneedd..
The study area of the project is located in thee Vienna Basin (E
Austria) and the southeasterly adjacent Eisenstadt-Sopron Basin (Fig. 1-1),
where natural fault zones are developed in Miocene sediments.
The fault investigated in stage 1 &2 is situated at the Eastern margin
of the Eisenstadt-Sporon Basin and has a length of a few kilometers in strike
and at least 40 m of height. This master fault and the associated smaller
faults in the hanging wall layers were mapped in a quarry and a three-
dimensional structural model was generated by from Terrestrial Laser
Scanning and Ground Penetrating Radar data.
The normal fault analyzed in stage 3, the Markgrafneusiedl fault in the
central Vienna Basin, has an extent of several tens of kilometers along strike
and reaches from the surface down to ~2250 ms of TWT down to the pre-
Neogene basement. The three-dimensional seismic dataset (Seymatzdue)
was provided by the OMV AG, together with existing interpretations of
stratigraphic horizons and borehole data.
Deformation around basin scale normal faults
21
Fig 1-1. Investigated areas (Vienna and Eisenstadt-Sopron Basins) positioned within the
structural map of the pre-Neogene basement (modified after Kröll & Wessely, 1993).
Normal faults are of particular importance in basin formation and
hydrocarbon development, whereby the major role can be subdivided in two
1.3 Normal fault systems - geometrical properties and linkage
processes
Deformation around basin scale normal faults
22
equally significant characteristics, i.e. fault geometry and role of interaction
and linkage between fault segments.
1.3.1 Listric faults
The most common interpretation of host-rock deformation is the
concept of a hanging-wall rollover anticline of layers above a listric normal
fault (Fig. 1-2) with or without syn-tectionic growth strata (e.g. Shelton,
1984; McClay and Scott, 1991). Three essential features characterize a
listric normal fault: a flat detachment surface, a rigid footwall, and rollover
anticline in the hanging wall (e.g. Shelton, 1984). Numerous models aimed
to reproduce the hanging wall deformation, whereby the most prominent is
the analogue model of McClay and Scott, 1991. The analogue model is based
on the rigid footwall that is thereby represented by a suitable shaped
cardboard upon which a rubber slice represents a listric fault curving into a
flat detachment at the base of the model.
Fig 1-2. Analogue model of growth strata deposited above an active listric normal fault, which
merges with a layer-parallel detachment at depth (modified after Yamada and McClay, 2002).
The hanging wall deformation pattern above a ramp-flat detachment
can be divided in four zones: (i) an upper zone of rotational deformation
adjacent to the upper and steeper part of the listric fault; (ii) a translation
zone producing the upper rollover and associated crestal collapse system,
(iii) a rotational zone encompassing the ramp syncline and the lower
sections of the rollover; (iv) a translation zone where the entire hanging wall
is translated horizontally above the flat detachment.
Deformation around basin scale normal faults
23
Generally, two kinematic groups of rollover systems are distinguished:
(1) the aforementioned fault rollovers induced by extensional displacement
along a listric fault whereby the footwall behaves as a rigid body (listric
faults sensu strictu) and (2) ‘expulsion rollovers’ which develop due to the
withdrawal of a weak material layer (e.g. salt or clay) within the footwall
layers (for a review see Krézsek et al., 2008; Dutton et al., 2004 and
references cited therein). By using scaled analogue experiments with layered
brittle and ductile materials Krézsek et al., (2008) simulated the
development of listric growth faults and expulsion rollover systems during
gravitational spreading of a passive margin sedimentary wedge detached on
salt (Fig 1-3).
Fig 1-3. Schematic diagram illustrating the effect of different overburden thickness on the
generation of listric faults above a weak layer (modified after Krezsek et al., 2008).
The results indicate that the mobilization of salt controls the strain
history of local faults developed in the sedimentary wedge. Hence, the
rollover kinematics is strongly related to sedimentation patterns and their
rate, i.e. portions with higher deposition rate will have a larger mass and
Deformation around basin scale normal faults
24
therefore such constellation of geological bodies can induce salt expulsion
resulting in a listric normal fault geometry.
Both models of listric normal faults have a different concept of the
behavior of the footwall. Unlike the rafting model that assumes a weak or
ductile detachment and footwall, the group of listric fault models sensu
strictu assumes that the footwall during ongoing deformation behaves as a
rigid body. In many cases, such an assumption has poor geological evidence
and is mechanically not valid if the footwall sediments are identical to the
hanging wall strata. Grasemann et al., 2005 listed several reasons that
contribute to the perception that fault footwalls are rigid. The first is due to
the fact that the drag effect in the footwall that can be much less than those
in hanging wall. A second reason that might contribute to the perception
that fault footwalls are rigid is that reverse drag on either side of the fault
may be associated with little or no drag on the opposing side, especially if
structural levels above or below the central marker are observed. Finally,
physical models of listric faults are simple based on a listric fault geometry
predefined by the model boundary conditions. However, more recent listric
models (Imber et al., 2003) revealed that footwall deformation can play an
import role, e.g. by footwall collapse where the active bounding fault steps
back into the footwall block.
1.3.2 Planar faults of finite length
Although concept of a listric fault is widely accepted, in many cases the
listric (downward-flattening) geometry of the fault surface is poorly
constrained, and is more an imposed conceptual model than an observation
(Barnett et al., 1987; Grasemann et al., 2005). In other words, often a
normal fault in nature is only partially constrained, as e.g. exposed fault
traces in an outcrop do not display the entire fault geometry, or the quality
of seismic data can decrease with depth so that the lower fault sections are
blurred.
Deformation around basin scale normal faults
25
In contrast, fault drag may actually occur along a planar (i.e. non
listric) fault of finite length, where slip results in a heterogeneous stress and
displacement field develop within the rock adjacent to the fault (Grasemann
et al., 2005, Fig 1-4).
Fig 1-4. Fault drag of a central marker along a normal fault. Normal drag refers to markers that
are convex in the direction of slip and reverse drag to markers that are concave in the direction
of slip (modified after Grasemann et al., 2005).
Using the linear elasticity theory, the geometrically idealized model
identified the influencing parameters which result in the formation of fault
drag. The discontinuous displacement along the slip surface is compensated
by a continuous deformation field in the adjacent matrix, which is also called
perturbation strain (e.g. Passchier et al., 2005). Due to this heterogeneous
deformation field, originally straight markers are deflected in the vicinity of
the fault. It was shown that exclusively the angular relationship between the
fault and the maker determines the type of drag, i.e. at low angles (<30°)
normal drag, at high angles (>30°) reverse drag is developed. Several other
numerical and analogue studies investigated the development of fault drag
(or flanking structures) around slip surfaces and analyzed the variable
geometries which occur in different flow kinematics and geometric
relationships between the fault and the markers (e.g. Grasemann et al.,
2003; Exner et al., 2004; Wiesmayr and Grasemann, 2005; Kocher and
Deformation around basin scale normal faults
26
Mancktelow, 2005 and 2006). Most importantly, all the models showed that
fault drag is developed in both hanging wall and footwall domain.
During progressive deformation, an initially straight marker line
passing through the centre of the fault is displaced. This deflected central
marker forms symmetrical folds, which are convex (i.e. normal drag) in the
direction of shear along the discontinuity; offset and deflection of the non-
central marker lines decrease towards the tips of the fault (Exner et al,
2004). This decrease in intensity of deflection is subsequently investigated in
the process of fault growth by segment linkage.
Conventional fault growth models suggest that the enlargement of
elliptical faults is a function of a progressive increase of displacement with
time (e.g. Walsh et al., 2002). Mechanically, a systematic increase of
displacement and fault length produces a larger fault. Linked normal faults
usually consist of complex zones of overstepping and linked segments that
affect fault geometry creating irregularities of the fault plane along strike
and dip. In addition to geometrical irregularities, a fault that is a result of
segment linkage through time displays irregular displacement patterns (see
chapter 5 Peacock, 2002). A good example of how geometry can vary along
a normal fault is illustrated in a summary figure of Marchal et al., 2003, see
Fig 1-5.
The most common technique used to analyze the accumulation of slip
and finite displacement on a fault are displacement – distance plots (D-x
plot). The success of this technique is largely due to the fact that fault
segments and linked faults exhibit a variability in displacement-distance
profiles, in contrast do isolated faults with continuous displacement profiles.
Such irregularities originate from the interaction and linkage of fault
segments.
1.4 Fault growth by segment linkage
Deformation around basin scale normal faults
27
Fig 1-5. Upper section: variations in normal fault shape: (1) the simplest shape for a blind fault
is an elliptical plane; (2) Fault shape affected by interaction with other features: restriction by
the ground surface; (3) Overlap with another fault plane forming a relay zone; (4) Intersection
with another fault plane. Three basic patterns that may combine to form complex fault shapes.
Lower section: (1) The half plane of a normal fault composed of a principal plane; (2)
Branched secondary fault planes at the vertical termination; (3) en-échelon secondary fault
planes at the lateral termination (modified after Marchal et, 2003).
Deformation around basin scale normal faults
28
Fig 1-6. Examples of displacement - distance profiles for individual fault segments: A-connected
fault, B-offset fault, C-nearly isolated fault, D-complex fault composed of fault segments
(modified after Peacock & Sanderson, 1991).
More recently, 3D geometrical analyses of fault surfaces, mostly
derived from 3D seismic data provided additional insight in different
segmentation patterns (e.g Marchal et al., 2003; Lohr et al., 2008). Using a
combination of both tools, a significant progress in deciphering of fault
segmentation patterns was achieved.
This thesis comprises several interrelated studies that are designed to
improve the knowledge of three-dimensional fault mechanics and fault-drag
development from basin- to outcrop- scale. The key questions that were
addressed by the thesis are:
(1) IS THE OCCURRENCE OF ANTICLINES IN THE HANING WALL OF A
NORMAL FAULT A RELIABLE INDICATOR FOR A LISTRIC FAULT SHAPE?
(2) CAN FAULT DRAG OCCUR NEAR LARGE BASIN-SCALE FAULTS?
1.5 Key questions addressed in the thesis
Deformation around basin scale normal faults
29
(3) IS IT POSSIBLE TO OBSERVE NORMAL AND REVERSE DRAG ALONG
THE OPPOSITE SIDE OF A LARGE NATURAL FAULT SURFACE?
(4) IS THERE A LINK BETWEEN INDIVIDUAL FAULT DRAG AND FAULT
DOMAINS, I.E. CAN FAULT DRAG SERVE AS INDICATOR OF SEGMENTS
AND/OR LINKAGE ZONES? IS THE MANGITUDE OF DRAG RELATED TO
THE SIZE OF THE FAULT PLANE?
(5) IS FAULT DRAG OF DIFFERENT TYPE (NORMAL OR REVERSE)
ANALOGOUS TO THE CORRESPONDING PERIODS OF FAULT GROWTH?
This PhD thesis was conducted within the FWF project “Modeling of
natural fault systems at various scales” and comprises results from three-
dimensional structural modeling of natural fault surfaces and the associated
deformation in the surrounding rock. Each phase of the research is
represented by a publication submitted or already approved for publishing in
international peer-reviewed scientific journals.
Following on this introductory chapter, the next part of the thesis
(chapter 2, based on an extended abstract in Trabajos de Geologia), is
focused on the ground-penetrating radar study conducted in a Miocene,
unconsolidated sediments at a gravel pit in the Eisenstadt-Sopron Basin.
Details about the various acquisition techniques, processing and finally the
construction of a 3D structural model are provided.
Since near-surface geophysical methods provided no satisfactory
insight in the deeper structural levels, in chapter 3 more detailed field
observations and the previously described shallow subsurface visualization
techniques were combined to construct a balanced cross section of the
1.6 Outline of the thesis
Deformation around basin scale normal faults
30
normal fault and the overlying sedimentary strata. This chapter is published
in the International Journal of Earth Sciences. The results of this study lead
to the conclusion that the listric fault model is not applicable for this normal
fault, and instead a reverse drag of markers along a planar fault of finite
length is proposed.
In Chapter 4, the effects of segment linkage were analyzed around a
large-scale normal fault from 3D seismic data of the central Vienna Basin.
From detailed fault analysis and mapping of the adjacent marker horizons,
numerous fault segments could be identified. Most importantly, the
usefulness of a detailed structural analysis of fault drag is demonstrated, as
individual segments can be determined from the distribution and magnitude
of fault drag. This chapter is submitted to the Journal of Geophysical
Research for publication.
A final synthesis in chapter 5 summarizes the results of the previous
chapters in a general context, discusses specific similarities and differences
of fault drag with respect to fault size and geometry, and finally gives an
outlook for further research focus arising from unsolved problems and
findings of this thesis.
Deformation around basin scale normal faults
31
References
Barnett, J. A. M., Mortimer, J., Rippon, J.H., Walsh, J.J., Watterson, J.,
1987. Displacement Geometry in the Volume Containing a Single Normal
Fault. American Association of Petroleum Geologists B 71, 925-937.
Exner, U., Mancktelow, N.S., Grasemann, B., 2004. Progressive
development of s-type flanking folds in simple shear. Journal of Structural
Geology 26, 2191–2201.
Exner, U., Dabrowski, M., 2010. Monoclinic and triclinic 3D flanking
structures around elliptical cracks. Journal of Structural Geology, in press.
Dutton, D. M., Lister, D, Trudgill, B.D., Pedro, K. 2004. Three-
dimensional geometry and displacement configuration of a fault array from a
raft system, Lower Congo, Offshore Angola: Implications for the Neogene
turbidite play. In: Davies, R.J., Cartwright, J.A., Stewart, S.A., Lappin, M.,
Underhill, J.R.. (Ed.), 3D seismic technology: Application to the exploration
of sedimentary basins. Geological Society, London, Memoirs, 29, 133-142.
Grasemann, B., Stüwe, K., 2001. The development of flanking folds
during simple shear and their use as kinematic indicators. Journal of
Structural Geology 23, 715-724.
Grasemann, B., Martel, S., Passchier, C., 2005. Reverse and normal
drag along a fault. Journal of Structural Geology 27, 999-1010.
Hamblin, W. K., 1965. Origin of "reverse drag" on the down-thrown
side of normal faults. Geological Society of America Bulletin 76, 1145-1164.
Hinsch, R., Decker K, Wagreich M, 2005. 3-D mapping of segmented
active faults in the southern Vienna Basin. Quaternary Science Revievs 24,
321-336.
Deformation around basin scale normal faults
32
Kocher and Mancktelow, 2005. Dynamic reverse modeling of flanking
structures: a source of quantitative kinematic information. Journal of
Structural Geology 27, 1346-1354.
Kocher and Mancktelow, 2006. Flanking structure in anisotropic
viscous rock. Journal of Structural Geology 28, 1139-1145.
Krezsek, C., Adam J, Grujic D, 2007. Mechanics of fault and expulsion
rollover systems developed on passive margins detached on salt: insights
from analogue modelling and optical strain monitoring. Geol Soc Lond Spec
Publ 292(1), 103-121.
Kröll, A., Wessely, G, 1993. Wiener Becken und angrenzende Gebiete.
Geologische Themenkarte der Republik Österreich 1:200.000. Geologische
Bundesanstalt. Wien.
Lohr, T., Krawczyk, C.M., Oncken, O., Tanner, D.C. 2008. Evolution of
a fault surface from 3D attribute analysis and displacement measuremants.
Journal of Structural Geology 30, 690-700.
Marchal, D., Guiraud, M., Rives, T., 2003. Geometric and morphologic
evolution of normal fault planes and traces from 2D to 4D. Journal of
Structural Geology 25, 135-158.
McClay, K. R., Scott AD, 1991. Experimental models of hanging wall
deformation in ramp-flat listric extensional fault systems. Tectonophysics
188, 85-96.
Passchier, C. W., 2001. Flanking structures. Journal of Structural
Geology 23, 951–962.
Passchier, C. W., Mancktelow, N. S., Grasemann, B., 2005. Flow
perturbations: a tool to study and characterize heterogeneous deformation.
Journal of Structural Geology 27, 1011-1026.
Peacock, D. C. P., Sanderson, D.J., 1991. Displacements, segment
linkage and relay ramps in normal fault zones. Journal of Structural Geology
13, 721 - 733.
Deformation around basin scale normal faults
33
Peacock, D. C. P., 2002. Propagation, interaction and linkage in normal
fault systems. Earth-Science Reviews 58, 121-142.
Pollard, D. D., Segall, P., 1987. Theoretical displacements and stresses
near fractures in rocks. . In: Atkinson, B.K. (Ed.), Fracture Mechanics of
Rock. Academic Press, London, pp. 277–349.
Resor, P. G., 2008. Deformation associated with a continental normal
fault system, western Grand Canyon, Arizona. GSA Bulletin 120, 414-430.
Shelton, W. J., 1984. Listric normal faults, an illustrated summary. Am
Assoc Petrol Geol Bull 68, 801-815.
Strauss, P., Harzhauser M, Hinsch R, Wagreich M, 2006. Sequence
stratigraphy in a classic pull-apart basin (Neogene, Vienna Basin). A 3D
seismic based integrated approach. Geol Carpathica 57, 185-197.
Tearpock, D. J., Bischke, R.E., 2003 Applied Subsurface Geological
Mapping. pp 821.
Walsh, J. J., Nicol, A., Childs, C., 2002. An alternative model for the
growth of faults. Journal of Structural Geology 24, 1669-1675.
Wiesmayr, G., Grasemann, B., 2005. Sense and non-sense of shear in
flanking structures with layer-parallel shortening: implications for
faultrelated folds. Journal of Structural Geology 27, 249–264.
Wiesmeyer, G., 2005. Kinematic and mechanical quantification of fault
related fold structures. Unpublished PhD Thesis. pp 79.
Yamada, Y., McClay K, 2003. Application of geometric models to
inverted listric fault systems in sandbox experiments. Paper 1: 2D hanging
wall deformation and section restoration. J of Struc Geol 25, 1551-1560.
Deformation around basin scale normal faults
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Deformation around basin scale normal faults
35
2. Possibilities of Ground Penetrating Radar
(GPR) in shallow subsurface 3D structural
modeling (an example from St. Margareten
gravel pit, Eisenstadt-Sopron Basin)
This chapter is a modified version of the extended abstract
Spahić D., Exner U., Behm M., Grasemann B., Haring A., Pretsch H. (in press): Structural 3D
modelling using GPR in unconsolidated sediments (Vienna basin, Austria). Vol.29. Trabajos de
Geologia.
presented at the Yorsget conference, Oviedo, June 2008.
Deformation around basin scale normal faults
36
Abstract
Field mapping and ground penetrating radar (GPR) measurements
were carried out near a gravel pit located at St. Margarethen, Burgenland,
Austria. The investigated area is located at the eastern margin of the
Eisenstadt-Sopron Basin, a subbasin of the Vienna Basin. In the gravel pit a
Middle Miocene succession consisting of layers of conglomerates, sandy
conglomerates, fine-grained sands and silts with variable thicknesses
between 1 and 4 m are exceptionally well exposed along a ~10 m high W-E
striking wall. The unconsolidated sediments are cut by numerous roughly N-
S striking high angle normal faults, offsetting, dragging and tilting the
sedimentary layering.
In order to obtain information about the third dimension of the
mapped fault structures, a network of sections parallel to the outcrop wall
and perpendicular to the faults was investigated with GPR applying centre
frequencies ranging from 40 MHz to 80 MHz.
A three-dimensional fault model was constructed from the results of
fault mapping and from georeferenced two-dimensional radargrams using
the structural modelling software Gocad. Structural and lithological
observations from the quarry walls provided crucial information for the
interpretation of the radargrams. Combining the fault and horizon mapping
from the individual GPR profiles with the information from the adjacent
outcrop, triangulated fault planes and sedimentary horizons were generated
in the structural model.
Deformation around basin scale normal faults
37
The investigation of fault surfaces through geological fieldwork is a
common approach to constrain kinematics, timing and structures related to
crustal tectonic processes. In many cases, investigated geological structures
are only partially exposed, restricting geoscientists to compile a geological
interpretation based on measurements and observations of the accessible
part of a geological structure. In order to achieve a more complete picture of
the structures in the subsurface, geophysical methods represent an essential
addition to field geological studies. One of the geophysical tools to analyze
shallow subsurface geology, Ground Penetrating Radar (GPR), has been
applied from sedimentary geology (e.g. Ékes and Hickin, 2001) , through
application in boreholes (e.g. Serzu et al., 2004) up to the non-geological
detection of buried mines or illegal waste (e.g. Daniels, 2004).
In recent years, GPR is widely used to study near-surface sediments
and more recently in near-surface structural geology. Ground Penetrating
Radar (GPR) surveys have been largely concentrated on unraveling of
various shallow sedimentary patterns. Beginning with the work of Ulriksen,
1982, the GPR technique has been applied in a large number of case studies
to image sedimentary structures, the architecture in the shallow subsurface.
Gradual entrance in field of structural geology was promoted by Meschede et
al., 1997 whereby use of 2D GPR unraveled rollover structures associated
with faults in a Middle Triassic limestone of SW Germany. In other studies,
2D radargramms visualized e.g. the hanging wall of active faults in the Betic
Cordillera applying high-resolution frequencies (Reiss et al., 2003), or the
delta facies and sedimentary architecture of Cypress Creek, West Vancouver
(Roberts et al., 2003). To infer the active Markgrafneusiedl Fault in
Pleistocene deposits and to correlate the structures with the deeper fault
2.1 Introduction
Deformation around basin scale normal faults
38
levels of the Vienna Basin, 2D GPR profiling was applied using the 40 and
500MHz frequency (Chwatal et al., 2005).
The faults investigated in this study crosscut a Miocene, poorly
consolidated succession of gravel and sand. In order to extend the
information from the exposed section and characterize the spatial
distribution of the faults in 3D, we conducted measurements with Multiple
Low Frequency (MLF) 40MHz and 80MHz GPR antennae in the area adjacent
to the outcrop wall. In addition to closely spaced (0.5m) 40 MHz sections
perpendicular to the strike of the faults, several 80 MHz sections were
recorded. The GPR coulisse sections that are perpendicular to the fault strike
demonstrate the utility of GPR data and surface mapping for investigation of
shallow structures (extension of fault traces). On the other hand, the results
of GPR application in unconsolidated near-surface material revealed the high
sensitivity of this geophysical method in respect to particular sediment and
humidity conditions.
The Vienna Basin is a pull-apart basin that developed during the
Oligocene/Miocene extrusion of the Eastern Alps towards the Pannonian
region in the E along sinistral, NE-SW trending strike slip faults and roughly
N-S trending normal faults. Part of this regional geodynamic setting is
recorded in extensional tectonics in unconsolidated sediments of the
Neogene Eisenstadt-Sopron Basin, a sub-basin of the Vienna Basin (Fig 2-1).
Along a W-E striking wall in a gravel pit 5 km SSE of St. Margarethen,
Burgenland, Austria, several generations of conjugate sets of W and
predominantly E-dipping normal faults are exposed in unconsolidated
sediments. In the 1:50 000 geological map of the area (REF!), a major fault
separating Badenian marls in the E from Sarmatian delta sediments in the W
is indicated (Fig. 2-2).
2.2 Regional setting, lithology and geometry of structural
features of the investigated area
Deformation around basin scale normal faults
39
Fig 2-1. Position of the researched area (black rectangle) (modified after, Hofmann, T (ed.),
2007)
Sediments in the W of the fault were deposited during the Middle
Miocene (Sarmatian and Pannonian age) and are successions of deltaic
gravels with intercalations of shallow marine calcareous sands (Fig 2-3)
(Sauer et al., 1992). Although the major fault surface is poorly exposed, the
Sarmatian layers in the hanging wall are accessible for detailed structural
analysis. The length of the faults ranges from several decimeters to several
tens of meters, (and most faults record a marked displacement gradient.
Deformation around basin scale normal faults
40
Measured offset of marker layers along exposed faults ranges from
centimeters up to several meters. Because there is a marked difference in
the compositions of the layered sequences (e.g. well-sorted conglomerate
consisting of coarse-grained pebbles alternating with fine-grained carbonate
rich sands), the markers are easily identified on the hanging wall and
footwall side of the faults.
Fig 2-2. Digital Elevation Model of Geological map of Austria, sheet Rust, 1:50000 (Herman et
al., 1991)
Deformation around basin scale normal faults
41
Fig 2-3. W-E striking outcrop wall in the gravel pit 5 km SSE of St. Margarethen, Burgenland.
Photo looking towards N. The darker layer in the middle of the wall consists of coarse grained
pebbles, which has been offset by numerous extensional faults mainly dipping towards W.
In order to extend the information of the two-dimensional exposure in
the St. Margarethen gravel pit in the third dimension with the aim to
construct a three-dimensional structural model, ground-penetrating radar
measurements were carried out in numerous sections parallel and
perpendicular to the outcrop wall using different transmitter antennas of 40
& 80MHz (Reiss et al., 2003; Sauer., 2004).
The GPR device consists of a plastic frame allowing the switch of
antennas represented as four metal pistons. Between the unshielded
antennas, the electromagnetic wave records measurements at the half
distance between them. The distance along the recorded sections was
measured with a tape, and as the instrument is not in direct contact with the
ground marks must be made at regular intervals.
The optimal depth for geological subsurface interpretation with the 40
MHz GPR unshielded antenna is at 15-20 m, although the maximal recording
depth of the device is down to 30 m, in comparison to only 9 m for a 80 MHz
antenna.. The quality of the radargrams is mostly dependant on the noise
level and the strata reflection energy. Another very important factor, which
causes a high noise level, is a rugged topography, as the wobbling of the
2.3 Ground Penetrating Radar (GPR) measurements
Deformation around basin scale normal faults
42
antenna causes interference in subsurface reflections recording patterns. In
order to locate the sections as accurate as possible, the geographical
positions were recorded with a differential GPS device (Trimble GeoXH, with
a horizontal accuracy of ca. 0.25 m).
The recorded radargrams were processed in Reflex (Sandmeier
Scientific Software), which is software for seismic reflection/refraction and
GPR processing and interpretation (see Chapter 2.1.3) for the 40MHz
radargram processing steps). The processed radargrams were georeferenced
using the recorded DGPS data in the three-dimensional visualization
software Gocad (Earth Decision).
2.3.1 Processing steps of the 40 and 80 MHz GPR radagrams
The GPR sections were collected in a step mode with the MLF 40 and
80 MHz system. The data were sampled with a step size of 0.5m and 2.40m
antennae spacing, marking every meter of along each section. The system
includes operator with back-pack (console, portable computer and 12V
battery) or remote cable extension.
Recorded radargram coulisse sections of a 40 and 80MHz data were
processed in Reflex (Sandmeier Scientific Software), which is specialized
software for seismic reflection/refraction and GPR data processing and
interpretation. Used velocity (distance/travel time) for electromagnetic (EM)
wave in this case was 0.12 m/ns, which is the speed of EM waves through
dry sand (Baker et al., 2007). The processing steps in Reflex software used
for the 40 MHz frequencies data are following:
•• ggeeoommeettrryy ccoorrrreeccttiioonnss iinn TTrraaccee IInntteerrppoollaattiioonn//RReessoorrttiinngg ooppttiioonn
((sseeccttiioonn lleennggtthh)),,
•• 22DD ffiilltteerr wwiitthhiinn BBaacckkggrroouunndd rreemmoovvaall aapppplliieedd ttoo ssmmooootthh eeaacchh ttrraacceess
wwiitthh oonnee rraaddaarrggrraamm sseeccttiioonn,, bbaannddppaassss ffrreeqquueenncciieess 1100--1155--6600--8800,,
aanndd
Deformation around basin scale normal faults
43
•• 22DD ffiilltteerr aapppplliieedd bbyy aavveerraaggee xxyy--FFiilltteerr ffoorr 33 ttrraacceess aanndd 33 ssaammpplleess..
Similarly, 80 MHz radargrams have almost the same processing steps:
•• ggeeoommeettrryy ccoorrrreeccttiioonnss iinn TTrraaccee IInntteerrppoollaattiioonn//RReessoorrttiinngg ooppttiioonn
((sseeccttiioonn lleennggtthh)),,
•• 22DD ffiilltteerr wwiitthhiinn BBaacckkggrroouunndd rreemmoovvaall aapppplliieedd ttoo ssmmooootthh eeaacchh ttrraacceess
wwiitthh oonnee rraaddaarrggrraamm sseeccttiioonn,, bbaannddppaassss ffrreeqquueenncciieess 4400--6600--111100--115500,,
aanndd
•• 22DD ffiilltteerr aapppplliieedd bbyy aavveerraaggee xxyy--FFiilltteerr ffoorr 33 ttrraacceess aanndd 33 ssaammpplleess..
In order to interpret the sections and to construct a structural model,
the two different frequencies the 40 MHz and 80 MHz radargrams, were
compiled in Gocad.
The processed radargrams were imported into Gocad and converted
from time to depth to attain a correct representation of the subsurface
geometries. Mapping of distinct structural features was performed on each
radargram. Reflectors which display a fairly continuous, rather flat pattern
which is traceable over a certain distance was identified as sedimentary
layering (Fig. 2-4). In contrast, fault surfaces cannot be directly identified in
the GPR sections, but need to be inferred from the disruption of sedimentary
layers. In this way, several sedimentary horizons and fault surfaces were
mapped and compiled to 3D planes from several sections.
At the investigated outcrop, normal faults occur either as isolated
segments, or as sets of high-angle faults dipping in the same direction, or
2.4 Structural 3D model in Gocad
2.5 Results and Discussion
Deformation around basin scale normal faults
44
finally as conjugate fault sets. Displacement magnitude (from centimeters
up to several meters) varies significantly between the different fault sets,
but also along the individual fault traces. In the outcrop, these faults of
confined length are associated with reverse drag of the adjacent
sedimentary layers. As a result of the displacement gradient from the center
towards the fault tips, and the close spacing of the individual faults, the
layering is rotated between the faults (Exner and Grasemann, 2010).
A difference in the radargrams of the 40 and 80 MHz GPR frequencies
is evident in Fig 2-4, as 40 MHz provide deeper but low-resolution
radargrams and 80 MHz are shallow but high-resolution sections (Fig 2-4).
The 80 MHz sections display some strata information about shallow
distribution of layering (Fig 2-4, right), but larger faults unfortunately are
not depicted.
After the GPR radargrams were processed, two types of structural
features can be identified exclusively on the 40 MHz frequency: (i) partial
imaging of fault traces (faults in fig 2-5) and (ii) tilting of sedimentary layers
between these faults. In addition, the reflection of particular marker horizons
and their offset along faults with offsets larger than 10 m can be clearly
mapped from the radragram sections using line-based fault and horizon
picking techniques.
Deformation around basin scale normal faults
45
Fig 2-4. 40 (left) and 80MHz (right) radargrams with marked (green ellipse) geological features
Importantly, a combination of frequencies provided satisfactory
resolution to exclude the hypothesis of a flat detachment directly below the
exposed normal fault set.
A three-dimensional, shallow subsurface structural model of
extensional faults in unconsolidated sediments was constructed applying
different techniques: (i) GPR recording of coulisse sections, (ii) DGPS
recording of the GPR sections, and (iii) field mapping of the outcrop. The
three-dimensional structural model provides basic information of structural
architecture behind the outcrop, recording no visible horizontal or
subhorizointal surface that might represent a flattened section of a listric
fault.
2.6 Conclusion
Deformation around basin scale normal faults
46
Fig 2-5. 3D model of a fault system. The colored surfaces are faults mapped behind the outcrop
wall by using 40MHz GPR radargrams.
Deformation around basin scale normal faults
47
References
Baker, G. S., Jol HM, 2007. An introduction to ground penetrating
radar (GPR). In: Bristow CS, Jol HM (eds) Ground penetrating Radar in
sediments. Geol Soc Lond Spec Publ 211, pp 1-18.
Bristow, C. S., Jol HM, 2003. Ground Penetrating Radar in Sediments.
Geol Soc London Spec Publ 211, 265.
Chwatal, W., Decker K, Roch K-H, 2005. Mapping active capable faults
by high-resolution geo-physical mathods: examples from the central Vienna
basin. Austrian J of Earth Sci 97, 52-59.
Daniels, D., 2004. Ground Penetrating Radar, 2nd Edition. pp 734.
Èkes, C., Hickin, E.J., 2001. Ground penetrating facies of the
paraglacial Cheekye Fan, southwestern British Columbia, Canada. Sedim.
Geol., 199-217.
Exner, U., Grasemann, B., 2010. Deformation bands in gravels:
displacement gradients and heterogeneous strain. J of Geol Soc. 167;
issue.5; p. 905-913.
Hermann, P., Pascher, G., Pistotnik, J. (1991): Geological map of
Austria: Sheet 78-Rust, Geologischen Bundesanstalt, Wien.
Hofmann, T., 2007. Wien, Niederösterreich, Burgenland. Wanderungen
in die Erdgeschichte. Dr. Fritz Pfeil, München 22, pp 167.
Meschede, M., Asprion, U. and Reicherter, K., 1997. Visualization of
tectonic structures in shallow-depth high resolution ground-penetrating
radar (GPR) profiles. Terra Nova 9, 167-170.
Reiss, S., Reicherter, K. R. and Reutner, C.-D., 2003. Visualization and
characterization of active normal faults and associated sediments by high-
resolution GPR. In: Bristow, C.S. & Jol, H.M (eds) Ground penetrating Radar
in sediments. Geol.Soc., London, Spec Pub 211, 247-255.
Deformation around basin scale normal faults
48
Roberts, M. C., Niller, H.-P. and Helmstetter, N., 2003. Sedimentary
architecture and radar facies of a fan delta, Cypress Creek, West Vancouver,
British Columbia. In: Bristow, C.S. & Jol, H.M (eds) Ground penetrating
Radar in sediments. Geol Soc London, Spec Pub 211, 111-126.
Sauer, D., Felix-Henningsen, P., 2004. Application of ground
penetrating radar to determine the thickness of pleistocene periglacial slope
deposits. J of Plant Nut Soil Sci 167, 752-760.
Sauer, R., Seifert, P., Wessely, G., Piller, W. E., Kleemann, E., Fodor,
L., Hofmann, T., Mandl, G., Lobitzer, H., 1992. Guidebook to excursions in
the Vienna Basin and the adjacent Alpine-Carpathian thrustbelt in Austria.
Mitteil Österr Geol Gesselschaft 85, 1-264.
Serzu, M.H., Kozak, E.T., Lodha, G.S., Everitt, R.A., Woodcock, D.R.
2004. Use of borehole radar techniques tocharacterize fractured granitic
bedrock at AECL’s underground research laboratory. J. of App. Geophys.
137-150.
Ulriksen, C. P. F., 1982. Application of impulse radar to Civil
Engineering. Ph.D. thesis Lund Univ of Techn , Lund, Sweden.
Deformation around basin scale normal faults
49
3. Listric versus planar normal fault geometry: an
example from the Eisenstadt-Sopron Basin (E
Austria)
This chapter is published as:
Spahić, D., Exner, U., Behm M., Grasemann, B., Haring, A., Pretsch, H. 2010. Listric versus
planar normal fault geometry: an example from Eisenstadt-Sopron Basin (E Austria).
International Journal of Earth Science. doi: DOI: 10.1007/s00531-010-0583-5
Deformation around basin scale normal faults
50
Abstract
In a gravel pit at the eastern margin of the Eisenstadt-Sopron Basin, a
satellite of Vienna Basin (Austria), Neogene sediments are exposed in the
hanging wall of a major normal fault. The anticlinal structure and associated
conjugated secondary normal faults were previously interpreted as a rollover
anticline above a listric normal fault. The spatial orientation and distribution
of sedimentary horizons and crosscutting faults was mapped in detail on a
laser scan of the outcrop wall. Subsequently, in order to assess the 3D
distribution and geometry of this fault system, a series of parallel ground
penetrating radar (GPR) profiles were recorded behind the outcrop wall. Both
outcrop and GPR data were compiled in a 3D structural model, providing the
basis for a kinematic reconstruction of the fault plane using balanced cross
section techniques. However, the kinematic reconstruction results in a
geologically meaningless normal fault cutting down- and up-section.
Additionally, no evidence for a weak layer serving as ductile detachment
horizon (i.e. salt or clay horizon) can be identified in stratigraphic profiles.
Instead, the observed deflection of stratigraphic horizons may be caused by
a displacement gradient along a planar master fault, with a maximum
displacement in the fault center, decreasing towards the fault tips.
Accordingly, the observed deflection of markers in the hanging wall – and in
a nearby location in the footwall of the normal fault – is interpreted as large
scale fault drag along a planar fault that records a displacement gradient,
instead of a rollover anticline related to a listric fault.
Keywords: Listric fault, fault drag, ground penetrating radar, balanced
cross section
Deformation around basin scale normal faults
51
Listric faults or shovel shaped faults (Suess 1909) are defined as
curved normal faults in which the dip decreases with depth resulting in a
concave upwards shape (e.g. Bally 1983; Shelton 1984). Two features are
considered as characteristic of listric normal faults (Wernicke and Burchfiel
1982): (i) a steep upper part of the normal fault flattening downwards or
merging with a low-angle detachment; and (ii) the down-warping or reverse
drag (Hamblin 1965) of the hanging wall block forming a rollover anticline.
Investigations of the origin of this widespread phenomenon that is very
often used as a tool in hydrocarbon explorations (Tearpock and Bischke
2003 and references therein) are predominantly focused on the importance
of fault shape. Broadly, two kinematic groups of rollover systems appear
common: fault rollovers induced by extensional displacement along a listric
fault shape and expulsion rollovers developed because of salt withdrawal
(e.g. Ge et al. 1997; Krézsek et al. 2007; Brun and Mauduit 2008, 2009).
Kinematic and geometric balancing techniques of extensional rollover
anticlines provided reconstructions of the depth of an underlying detachment
horizon (Chamberlin 1910; Wernicke and Burchfiel 1982; Tearpock and
Bischke 2003). The understanding of the geometric evolution of listric fault
systems was significantly improved by employing scaled analogue models
(e.g. McClay 1990; McClay and Scott 1991; Xiao and Suppe 1992; Yamada
and McClay 2003; Dooley et al. 2003) and more recently numerical models
(Crook et al. 2006). Analogue models comprise a deformable hanging wall,
composed of unconsolidated sand that is extended over a rigid footwall block
(Yamada and McClay 2003). By employing rigid footwall blocks, the
geometry of the master fault is predefined by the footwall block shape and
remains fixed throughout the deformation history. However, some authors
suggested that footwall deformation or collapse could be important
3.1 Introduction
Deformation around basin scale normal faults
52
mechanisms during extension along listric faults (Gibson et al. 1989; Brun
and Mauduit 2008; Krézsek et al. 2007), which are inherently neglected in
analogue models or balancing techniques assuming a rigid footwall. Based
on mechanical arguments, the common assumption that a hanging wall
rollover anticline automatically implies a listric fault geometry (e.g. Shelton
1984; Yamada and McClay 2003) was questioned by several authors (e.g.
Barnett et al. 1987; Mauduit and Brun 1998; Grasemann et al. 2005; Brun
and Mauduit 2008). Alternatively, reverse drag of strata both in the hanging
wall and in the footwall may develop around a planar fault surface, where
the displacement decreases towards the fault tips (e.g. Barnett et al. 1987;
Gupta and Scholz 1998; Mansfield and Cartwright 2000).
In this study we investigate a normal fault system in a southeastern
satellite basin of the Vienna Basin (Austria), where tilting of sediments close
to the fault was previously interpreted as a rollover anticline associated with
a listric fault geometry (Decker and Peresson 1996). This paper focuses on
the exposed hanging wall of the normal fault, comprising (1) field mapping
supported by terrestrial laser scanning of the outcrop (2) GPR imaging of the
deformed sediments and (3) geometric reconstruction of the fault geometry
by coulisse cross section balancing. An integrated structural model is used to
discuss the plausibility of a listric normal fault.
The Vienna Basin, located between the Alpine- and the Carpathian
mountain belt, formed in the Miocene as a result of the lateral extrusion of
the Eastern Alps (Royden 1985; Ratschbacher et al. 1991). Mostly SW-NE
trending transtensive strike-slip and normal faults permitted the deposition
of up to 5000 m of marine to lacustrine sediments in the center of the basin
from the Carpathian fold belt and Pannonian basin (e.g. Fodor 1995). The
multi-staged tectonic evolution started with a piggyback basin in the Lower
Miocene positioned on the top of Alpine advancing thrust sheets (Wagreich,
3.2 Regional setting
Deformation around basin scale normal faults
53
2000), followed by a pull-apart stage in the Middle to Upper Miocene. After a
Pannonian basin inversion phase, E-W extension lasted at least until the
Pleistocene (Decker 1996) and is probably still active (Chwatal et al. 2005;
Decker et al. 2005; Hinsch et al. 2005). The basin was extensively studied
for hydrocarbon exploration (Wessely 1988; Strauss et al. 2006).
In the southeast, the Vienna Basin is connected to the Eisenstadt-
Sopron Basin, which is a small satellite basin with 2000 m of sediment infill.
The economically less important and thus less explored basin is bordered by
normal faults (Fig. 3-1) and experienced its main subsidence phase in the
Badenian (Schmid et al. 2001). The eastern margin of the basin is defined
by the N-S trending Köhida normal fault system (Fodor 1995).
Fig.3-1 Tectonic sketch map of the Eisenstadt-Sopron Basin (eastern Austria).The investigated
gravel pit is located on the eastern basin margin, 5 km south of the village St. Margarethen. A
normal fault (referred to as master fault in the text) juxtaposes Badenian silts and limestone in
the E with Sarmatian and Pannonian gravels and sands in the W (modified after Schmid et al.
2001)
Deformation around basin scale normal faults
54
The investigated outcrop (Fig. 3-2) is situated at the eastern margin of
the Eisenstadt-Sopron basin, along a NNE –SSW striking normal fault, a part
of the Köhida fault system, displacing Badenian calcareous silt in the East
against a succession of Sarmatian and Pannonian gravels and calcareous
sands in the West (Harzhauser and Kowalke 2002). In the southern part of
the investigated area, both footwall and hanging wall sediments are covered
by Pleistocene gravels, which post-date the activity of the normal fault.
Approaching the fault plane, the hanging wall strata record an increase in
dip angle from West to East, which was interpreted as rollover anticline
associated with a listric normal fault by Decker and Peresson 1996.
Fig. 3-2 Detailed map showing the investigated outcrop walls and GPR location in the gravel pit
and the surrounding geology. The master fault juxtaposes Badenian marls and limestones in the
E with Sarmatian and Pannonian gravels and sands
3.3 Data acquisition, processing and results
Deformation around basin scale normal faults
55
The investigated outcrop is located inside a gravel pit situated ca. 5km
south of the village St. Margarethen, Burgenland, Austria (Fig. 3-1). A WNW-
dipping normal fault (referred to as master fault in the following text) was
mapped along the eastern margin of the pit (Decker and Peresson 1996).
While the footwall of the master fault consisting of Badenian sediments is
hardly exposed, the hanging wall comprising a sequence of middle Miocene
(Sarmatian and Pannonian) gravels, silts and sands (Harzhauser and
Kowalke 2002) can be studied in detail. The sedimentary beds are tilted up
to ca. 35° towards the master fault, forming an anticlinal structure in the
hanging wall of the master fault (Fig. 3-3a).
Fig. 3-3 Equal area projections, lower hemisphere: a poles to bedding planes (29) and b poles
to fault planes (90), max. value: 16.2% at 311 / 62, contours at: 1.20 measured along the
northern wall.
Additionally, several smaller normal faults with variable length and
displacement, oriented subparallel and conjugate to the master fault,
crosscut the sedimentary beds (Fig. 3-4b). In order to generate a 3D
structural model and constrain the geometry and kinematics of the master
fault, the following methods were applied: (i) detailed structural
measurements of the sedimentary layers and the exposed faults, (ii)
terrestrial laser scanning to obtain a high-resolution digital surface model
Deformation around basin scale normal faults
56
and georeferenced, rectified image of the outcrop wall, (iii) GPR survey
behind the scanned wall to image the unexposed 3D geometry of the
sedimentary beds and faults, and (iv) 2D section balancing to reconstruct
the geometry of the proposed listric normal fault at depth. Combining these
datasets, we generated a 3D structural model of the normal fault and the
deformed hanging wall sediments.
3.3.1 Structural data
The investigated outcrop is located at the northeastern margin of the
gravel pit, where a 10 m high and 30 m wide E-W oriented wall exposes the
Sarmatian-Pannonian succession in the hanging wall of the master fault (Fig.
3-2).
We identified five characteristic marker units (M1-M5 in Fig. 3-4b) in
the exposed section which were later used for correlation with horizons
mapped in the GPR data.
Along the outcrop, the dip of the planar sedimentary layers increases
gradually from W to E, with a dip towards the E of 8° in the W to a
maximum of 34° in the E. This anticlinal structure was earlier interpreted as
an expression of hanging wall collapse above a listric normal fault (Decker
and Peresson 1996). In detail, the increase of dip is not only related to a
gentle folding, but dip variations occur abruptly at secondary normal faults
oriented parallel and at a conjugate angle to the master fault (Fig. 3-4b).
Most of the observed faults are more accurately described as deformation
bands (Exner and Grasemann, 2010), restricted to the lower gravel in M2
and displacing the sedimentary layering only some few centimeters.
Deformation around basin scale normal faults
57
Fig.3- 4 a Map view of the investigated site, depicting the position of the scanned outcrop wall
and the location of the GPR site; b Geological interpretation of the investigated wall, identifying
the marker horizons (M1-M5), faults (marked in yellow) and deformation bands (blue); c-f GPR
Deformation around basin scale normal faults
58
sections N of and roughly parallel to the outcrop wall. Profile c is at ca. 6 m distance from the
wall, the distance between the individual profiles is between 0.5 and 1.5 m as indicated in Fig.
3-4a. Variations in reflection intensity are interpreted as marker horizons, i.e. variation in
lithological composition, most of which can be traced in all four sections. Subvertical offsets in
the GPR signal can be correlated with larger fault structures; the fault F1 is observed in all
sections, while the signals of F1 and F3 are lost further to the N.
These small faults record a displacement gradient from the center
towards the tips, which promotes the development of reverse drag in the
adjacent sedimentary layers (Hamblin 1965; Grasemann et al. 2005).
Propagation and rotation of some faults lead to vertical coalescence and the
generation of faults with larger offset up to a maximum of 4 m, crosscutting
the entire exposed section. As all of the observed long faults cut across
sedimentary horizons with a documented hiatus of several thousands of
years (Harzhauser and Kowalke 2002), and no increase in thickness of the
Sarmatian beds towards the master fault is documented, a synsedimentary
generation of these faults can be ruled out.
Borehole data from a groundwater exploration drilling, located inside
the gravel pit ca. 100 m SW of the outcrop wall (marked in Fig. 3-2), do not
provide any indication of a possible detachment horizon, i.e. salt or silt,
down to a depth of 20m below the exposed section. Instead, the succession
of Sarmatian gravels and sands continues without any notable disturbances.
3.3.2 Ground Penetrating Radar
Ground penetrating radar (GPR) is commonly employed for detecting
near surface geological features in sediments (e.g. Bristow and Jol 2003).
Furthermore, several recent studies document the applicability of this
method for the detection of faulted sedimentary horizons in the shallow
subsurface. Meschede et al. (1997) observed the tectonic surfaces and
rollover structures associated with faults in Middle Triassic limestone of SW
Germany along 2-D profiles. The hanging wall of active faults was visualized
Deformation around basin scale normal faults
59
in the Betic Cordillera (Reiss et al. 2003) with high frequency antennas. To
infer the active Markgrafneusiedel Fault in shallow Pleistocene deposits and
to correlate it with the deeper fault levels of the Vienna Basin, 2-D GPR
profiling was applied using both low and high frequencies (Chwatal et al.
2005).
A dense network of parallel GPR profiles provides the opportunity to
image sedimentary horizons and faults in the prolongation along strike N of
the exposed section. The investigated site was a 20 m x 19 m sized area
(Fig. 3-4a). Though several antennae frequencies where applied and tested,
we restrict the interpretation to the best results obtained with a center
frequency of 40 MHz. The raw data are of moderate quality and gain
significance by a simple but effective signal processing (background
removal, bandpass filtering 15 to 80 MHz, weak smoothing). There is a low
signal to noise ratio (S/N ratio) in the raw recordings. The reason for this
remains unclear since disturbing surface features are absent and the soil
was rather dry. However, strong reverberations suggest the presence of
fluids. We interpret that although the extensive tree cover was recently
removed, the still existing roots contain a relatively high amount of water.
Forty-one 40 MHz GPR sections were collected along 20 m long, E-W
oriented lines with a relative spacing of 0.5 m. The sections are parallel to
the exposed wall and perpendicular to the N-S striking faults. Assuming a
propagation velocity of 0.12 m/ns (Bristow and Jol 2003), the signal
penetration depth is approximately 15 m. The processed GPR sections were
interpolated into a depth-converted cube such that sections with arbitrary
directions can be visualized. Since the topography is rather flat and even, no
topographic correction was applied.
Four representative GPR profiles striking parallel to the outcrop wall
(Fig. 3-4a) are presented in Fig. 3-4,c-f. The strong reflections, located
between 3 and 6 m below the surface, can be correlated with the M2 gravel
horizons identified in the outcrop section. Below, the marker horizons M4,
Deformation around basin scale normal faults
60
M5 and M6 can be tentatively assigned to single high reflectors in the
individual sections. Most reflectors slightly dip towards the E, or show an
undulating geometry. Abrupt disturbances, representing a lack of energy in
an otherwise continuous reflection band, are interpreted as faults. Some
faults (e.g. F1) can be identified in several sections, thus providing
additional constraints on their strike direction (Fig. 3-4a). The 40 MHz
antenna did not depict smaller sized faults mapped in the outcrop, which
have less than 3 m in length and correspondingly only some centimeters or
decimeters of displacement. Finally, another strong reflector M6, which is
not exposed at the nearby outcrop wall, was recorded in most 40 MHz GPR
sections. This horizon, approximately 17 m below surface (and ~7 m below
the base of the exposed wall) conspicuously dips in the opposite direction to
the upper reflectors, i.e. 25° to the SW.
3.3.3 Laser scan and 3D model
We used a terrestrial laser scan (TLS) system (RIEGL LMS-Z420i),
consisting of a high-performance long-range 3D laser scanner and a
calibrated high-resolution digital camera mounted onto the scanner head, to
generate a digital surface model and a rectified image of the investigated
outcrop wall. The entire wall and the surroundings were scanned from a
single point, which was recorded using a Differential Global Positioning
System receiver (DGPS). The point-cloud of xyz-coordinates acquired by TLS
was imported into Gocad, a three-dimensional visualization software, and
the points corresponding to the outcrop wall were meshed to form a virtual
outcrop surface, onto which the rectified image was draped (McCaffrey et al.
2005). By integrating the measurements of the respective bedding and fault
planes, a 3D structural model of the outcrop data was generated (Fig. 3-5),
taking account of the exact location and orientation of the structural
features. To compare the structural measurements collected at the outcrop
wall with the GPR imaging results, we integrated both datasets into the 3D
model, providing the framework for the further structural interpretation.
Deformation around basin scale normal faults
61
Apart from digitizing numerous faults along the outcrop wall, three
distinctive fault surfaces were additionally mapped in the GPR dataset.
Although the outcrop wall is located at a rather large distance (ca. 6 m) from
the closest GPR section, we were able to connect the fault traces from the
GPR sections with three of the larger faults in the outcrop and construct
strike and dip of the fault planes. Similarly, the well traceable marker
horizons M2 and M6 were connected to horizon surfaces in the structural
model (Fig 3-5).
Fig. 3-5 3D structural model constructed from the rectified outcrop image draped on terrestrial
laser scan (TLS) data and the ground penetrating radar (GPR) cube (in the background). No
vertical exaggeration. The exposed fault and horizon surfaces are constructed in great detail,
accurately respecting the dip and dip direction of each element. Selected fault and horizon
surfaces mapped from GPR data are connected to the outcrop structures (e.g. F1).
Deformation around basin scale normal faults
62
A great number of geometrical reconstructions of extensional faults
has been proposed and discussed by several authors (e.g. Davison 1986;
Williams and Vann 1987; White 1992; Yamada and McClay 2003). Most of
these models are based on the geometric relationships between the hanging
wall structures and the underlying detachment using vertical, oblique or
flexural slip restoration assuming either conservation of the area/bed-length
on a cross-section and/or constant slip along the fault (for a discussion of
models with area change and slip gradients see Wheeler 1987). All these
models have in common that sediments in the hanging wall above a rigid
fault surface with a listic geometry deform into a rollover anticline, while the
footwall remains undeformed (Tearpock and Bischke 2003 and references
therein). Comparing different reconstruction techniques with a positive
inversion analogue experiment, Yamada and McClay (2003) suggested that
the inclined simple shear model most accurately approximates the
restoration of the hanging wall deformation. This technique assumes that
deformation of the hanging wall occurs by simple shear along inclined slip
planes, which are either parallel to syn- or antithetic faults (White et al.
1986; Dula 1991). The shear angle of these faults is frequently estimated
using the Mohr-Coulomb Theory resulting in dip angles between 60°-70°
(Tearpock and Bischke 2003). In order to reconstruct the master fault
geometry from a hanging wall rollover anticline, the heave of a marker
horizon must be known. The bed thicknesses along the shear planes remain
fixed and therefore this technique always results in a hanging wall area-
balanced reconstruction. Practically, the marker horizon is divided into
domains of constant dip and the amount of displacement between the dip
domains is defined by the distance along the plane between the
reconstructed and the deformed geometry of the marker horizon.
3.4 Depth to detachment construction assuming a listric fault
geometry
Deformation around basin scale normal faults
63
Being aware of the limitations of geometrical reconstructions, we used
the inclined simple shear model in order to reconstruct the depth of the
detachment, assuming that a rigid listric fault forced the deformation of the
marker horizon M3 of the northern and southern pit walls in St. Margarethen
(Fig. 3-2). The most sensitive parameter, which strongly influences the
location and the orientation of the detachment, is actually the spatial
position constrained by the widths and orientations of the dip-domains with
respect to the orientation of the fault plane containing the hanging wall
cutoff of the marker horizon. Therefore, the dip domains were constructed
as accurately as possible using the 3D structural model including the
exposed sections of M3 as well as its spatial orientation in the subsurface.
According to the mean of the measured fault planes in the hanging wall (Fig.
3-3b), the dip of the inclined shear planes is 72°. The fault plane containing
the hanging wall cut-off of the marker horizon M3 dips 60° towards WNW.
Our depth-to-detachment calculations of both the northern and southern pit
walls in St. Margarethen gave almost identical but geologically meaningless
results, because the constructed detachments do not flatten at depth but
have an U-shaped geometry (Fig. 3-6). The construction of the domain
closest to the observed master fault results in a plausible initial flattening of
the detachment segment in the next domain. However, the constructed
detachment segments of all other domains record continuous steepening
and dip in the opposite direction than the steep part of the exposed fault at
the surface (i.e. towards ESE) resulting in the geologically meaningless U-
shape fault geometry. We therefore conclude that the assumption of a rigid
listric fault plane for the normal fault in St. Margarethen might be incorrect
and other mechanisms were responsible for forming a hanging wall anticline.
Deformation around basin scale normal faults
64
Fig. 3-6 Balanced cross sections, a north wall and b south wall, using a dip domain technique in
order to reconstruct the continuation of a listric fault at depth (Tearpock and Bischke, 2003).
We omitted a full-scale graphical reconstruction in order to avoid an abundance of auxiliary
lines. The input parameters into the models are (i) the spatial orientation of the marker bed M3
and (ii) the true dip of the master fault at the hanging wall cutoff level. Both reconstructed
sections do not result in a listric fault with a sub-horizontal detachment at depth but in
geologically meaningless structure.
3.5.1 Listric versus planar fault geometry
Since both concepts of fault related deformation, i.e. a rollover
anticline above a listric fault as well as reverse drag in the hanging wall of a
planar fault, result in similar finite geometries, their respective applicability
to the studied outcrop is discussed in the following section. Importantly, this
study is restricted to mechanical models of anticlines related to normal
faults, and does not consider hanging wall anticlines occurring along inverted
normal faults related to a compressional reactivation with thrust kinematics
(e.g. McClay, 1995).
3.5 Discussion
Deformation around basin scale normal faults
65
Balancing techniques of listric faults are based on the concept of the
displacement of the hanging wall along a curved fault surface, separating the
deformable sedimentary pile in the hanging wall from an undeformable
footwall (Fig. 3-7a). In these models, the shape of the fault largely controls
the deformed geometry of the hanging wall. The success of the model of
listric faults is largely based on the highly intuitive results of sandbox models
(e.g. McClay 1990; McClay and Scott 1991), which result in geometries
directly comparable to interpreted extensional faults from seismic sections
(e.g. Bally 1983; Butler 2009). Since listric faults and associated hanging
wall anticlines are common targets for hydrocarbon exploration, the
balancing methods like the technique applied in this study have been widely
used in order to support seismic interpretations (e.g. Gibbs 1984; Williams
and Vann 1987). In order to increase the fit between observations and
models, numerous modifications of the model and the balancing technique
have been suggested (for a review see Tearpock and Bischke 2003; Yamada
and McClay 2003), some of which even imply deformation of the footwall
(e.g. Koyi and Skelton 2001; Imber et al. 2003; Krészek et al. 2007). Our
simple restoration of the extensional fault in St. Margarethen does not result
in a geologically plausible subhorizontal lower part of a listric fault. The
applied method is based on the assumptions of listric fault models but the
constructed results are geologically meaningless and therefore we conclude
that extension and hanging wall deformation were controlled by a different
mechanical process.
A completely different group of models explain rollover structures (Fig.
3-7b), also referred to as reverse drag (Hamblin 1965), by displacement
gradients along the fault (e.g. Barnett et al. 1987; Watterson et al. 1998).
These models account for the frequent observation that a fault of finite
length records lateral and vertical variations in displacement magnitude (e.g.
Mansfield and Cartwright, 2000). Such a displacement gradient induces wall-
rock strains eventually leading to a bending, i.e. reverse drag, of markers at
a high angle to the fault plane (Grasemann et al. 2005).
Deformation around basin scale normal faults
66
Fig. 3-7 Generalized cross sections comparing the two conceptual models. a Listric fault
model with constant displacement along a fault, which flattens at depth into a sub-horizontal
detachment. The hanging wall is deformed into a rollover anticline but there is no deformation
within the footwall. b Model of a planar fault of finite length recording a displacement gradient.
Fault movement induced perturbation strain which causes reverse drag in the hanging wall and
in the footwall. The exposed section in St. Margareten record nearly identical geometry that
characterizes the both models. c Outcrop picture of the Oslip quarry (location marked in Fig. 3-
1) in a footwall position along the N-S trending fault system, exposing Badenian limestone and
sand layers dipping to the E with ca. 40°, which is interpreted as reverse drag and associated
deformation bands in the footwall of the normal fault.
The faults in these models are planar and not listric, and even slip
gradients along “anti-listric” faults may often result in reverse drag (Reches
and Eidelman 1995). If such a displacement gradient model is applied to the
studied outcrop in St. Margarethen, the reverse drag observed in the
hanging wall Sarmatian sediments may alternatively be explained by a slip
gradient along a planar master fault. The deformation in the Sarmatian
sediments is accommodated by secondary faults and deformation bands of
finite length, which themselves record a displacement gradient and
associated smaller scaled reverse drag (Exner and Grasemann 2010).
Deformation around basin scale normal faults
67
Because the master fault exposed in the gravel pit of St. Margarethen
cannot be traced further to the S across the Austrian-Hungarian border,
where there is no evidence of extension in the Sarmatian/Pannonian
sediments, a slip gradient on the master faults is geologically highly
plausible. Displacement gradient as the primary mechanism for the drag in
the Sarmatian sediments is furthermore supported by the GPR data and the
integrated 3D structural model (Fig. 3-5), which show that the magnitude of
the drag of marker horizons is changing along the strike of the master fault.
Although the displacement gradient models predict fault drag in the hanging
and the footwall, the magnitude and sense is strongly dependent on the
exposed part of the fault and theoretically can juxtapose reverse drag in the
hanging wall with normal or no drag in the footwall (Barnett et al. 1987;
Grasemann et al. 2005). Unfortunately, the footwall in the quarry in St.
Margarethen is not exposed. However, in direct continuation along the strike
of the normal fault system to the N (Fig. 3-1, quarry Oslip), the Badenian
sediments in the footwall of the master fault are strongly deformed by the
formation of deformation bands and record a dip of 30° towards the W (Fig.
3-7c). We interpret that this tilt of the Badenian sediments below the master
fault represents the footwall reverse drag. Based on the regional geological
map, the dip variations of the Badenian sediments are clearly related to the
faulting and therefore favour models which predict footwall deformation.
3.5.2 Hydrocarbon traps
The occurrence of hydrocarbon-trapping listric fault systems has been
of great interest for oil and gas exploration around the world (e.g. Dula
1991; Nunns 1991; Withjack et al. 1995; Desheng 1996; Rowan et al. 1998;
Bhattaracharya and Davies 2001; Dutton et al. 2004). Rollover anticlines are
the least risky traps for petroleum depending on the juxtaposition of a shale
seal across the fault plane (Allen and Allen 2005). The fault plane itself may
or may not seal, allowing either lateral or vertical migration to higher
structural levels (Weber 1978). However, detailed subsurface mapping of
Deformation around basin scale normal faults
68
listric faults frequently extends below the level of coherent seismic data
decreasing the reliability of interpretation. Furthermore, it has been shown
that flattening normal faults are disappearing in the seismic data with
increasing depth (“downwards dying growth faults”, e.g. Tearpock and
Bischke 2003). Consequently, refined balanced cross section techniques (see
recent review by Poblet and Bulnes, 2005), analogue (e.g. Vendeville and
Cobbold 1988; Gaullier et al. 1993; Mauduit and Brun 1998), and numerical
(Erickson et al. 2001 and references cited therein) models have been used in
order to aid seismic interpretations. Especially mechanical models
introducing interaction between a newly formed steep normal fault and a
pre-existing ductile low-angle detachment layer, have increased the
knowledge about plausible rheological and geometrical settings for normal
faults, which flatten at depth. However, it is important to note that a large
number of models which introduce ductile layers are strictly speaking not
listric faults sensu strictu but can be better explained by a raft tectonic
model, which is based on mechanical instabilities (Mauduit et al. 1997).
Here we argue that planar faults recording a displacement gradient
may result in similar geometries as listric faults with rollover anticlines. This
model is especially attractive, where (i) the fault records a high-angle
relationship with the marker layers, (ii) the fault cuts rocks of similar
material behaviour in the hanging wall and in the footwall, (iii) the fault has
a finite length and records a displacement gradient and (iv) no ductile layer
(e.g. salt) is present at depth. An exceptional illustrative example has been
investigated by a detailed 3D seismic interpretation of extensional faults in
the Leona field in the Eastern Venezuela Basin (Porras et al. 2003). In this
interpretation, the major oil accumulations are confined to seals forming
normal and reverse drag folds along faults with displacement gradients.
Normal-drag folds form the largest traps, with extended reservoirs in the
footwall of master normal faults, whereas reverse-drag folds provide the
structural closure for trapping in the hanging wall.
Deformation around basin scale normal faults
69
We created a 3D structural model of deformed Sarmatian and
Pannonian Sediments in the hanging wall of a normal fault bordering the
eastern margin of the Eisenstadt-Sopron Basin. Spatial field measurements
of faults and sedimentary layering, a terrestrial laser scan of an outcrop wall
and GPR data behind the outcrop wall were integrated into the structural
model. The dip of the sediments increases towards the west-dipping master
fault resembling a rollover structure above a listric normal fault. However,
balanced cross sections based on standard dip domain techniques used for
construction of listric faults do not result in geologically plausible structures.
Considering the absence of a ductile horizontal layer at depth and the fact
that the master fault terminates along strike towards the S, we argue that
the observed reverse drag in the sediments is related to a slip gradient along
a planar normal fault of finite length.
AAcckknnoowwlleeddggeemmeenntt
This study was funded by the Austrian Science Fund (FWF-Project
P20092-N10). We thank K. Decker, M. Wagreich and M. Harzhauser for
discussion and providing information about earlier exposure conditions of the
gravel pit. Constructive reviews by S. Philipp and anonymous reviewer, and
editorial comments by R. Greiling are gratefully acknowledged.
3.6 Conclusions
Deformation around basin scale normal faults
70
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4. Identifying fault segments from 3D fault drag
analysis
This chapter is based on: Spahić D, Exner U., Grasemann B. Identifying fault segments from 3D
fault drag analysis. To be submitted to the Journal of Geophysical Research.
Deformation around basin scale normal faults
78
Abstract
The influence of segmented fault growth in Miocene sediments of the
central Vienna Basin is demonstrated by a combination of three-dimensional
geometric and kinematic parameters. In detail, we investigate marker
horizons in the hanging wall and footwall of with the highly irregular
Markgrafneusiedl normal fault surface from 3D seismic data. In addition to
conventional fault analysis, e.g. orientation, displacement and curvature, we
focus our study on the occurrence of normal and reverse drag of marker
horizons, predominately in the hanging wall. By analyzing the relationship
between fault surface geometry and fault drag within the marker horizons
we are able to identify individual fault segments and constrain several
stages of progressive fault evolution. By a detailed analysis of fault drag,
fault segments may be detected which are not recorded by displacement
maxima or fault morphology in equivalent detail. In addition, tracking of
marker deflections geometries in the hanging wall facilitates the
identification or prediction of equivalent structures in the footwall, which are
obliterated in seismic data by the fault shadow, but may represent
unconventional hydrocarbon traps in the footwall of a normal fault.
Deformation around basin scale normal faults
79
The concept of fault growth by segment linkage is a common method
used to explain the processes of fault evolution on various scales. Processes
of segment linkage have been investigated from a micro and meso scale
(e.g. Childs et al., 1996; Kristensen et al., 2008) up to the regional
deformations (Peacock and Sanderson, 1991; Kelly et al., 1998; Gawthorpe
et al., 2003; Marchal et al., 2003; Walsh et al., 2003; Davis et al., 2005).
The segment linkage model assumes a progressive growth scheme, whereby
the properties of a mature fault surface are a product of cumulative
displacement increase due to the progressive enlargement and coalescence
of individual segments (e.g. Nicol et al., 1995; Peacock, 2002; Walsh et al.,
2002). Commonly, identification of fault segments is accomplished by
analysis of the displacement distribution on the fault, which is sometimes
combined with studies of fault morphology (e.g. Watterson, 1986; Barnett et
al., 1987; Walsh and Watterson, 1989; Cartwright et al, 1995; Contreras et
al., 2000; Kim and Sanderson, 2005; Marchal et al., 2003; Lohr et al.,
2008).
Displacement along an isolated elliptical fault typically shows a
decrease from the fault center to the tips (Walsh and Watterson, 1989). To
accommodate this displacement gradient along the fault, adjacent marker
layers show a deflection towards the fault commonly described as reverse
fault drag, compensating the discontinuous displacement along the fault by a
continuous displacement within the host rock (Barnett et al., 1987; Peacock
and Sanderson, 1991; Reches and Eidelman, 1995; Gupta and Scholz, 2000;
Grasemann et al., 2005). This conceptual model of the synchronous and
mechanically related development of a hanging wall anticline and a footwall
syncline adjacent to a normal fault is especially favorable in the case where
a connection to a low-angle detachment fault at depth is not evident.
4.1 Introduction
Deformation around basin scale normal faults
80
In this work, a high-resolution commercial 3D seismic dataset was
analyzed, providing excellent spatial imaging of a ~16km long segment of
the Markgrafneusiedl normal fault in the Vienna Basin, Austria. By detailed
mapping of the fault plane and associated syn-and anticlines in the adjacent
marker horizons a 3D structural model was created. From the depth-
converted geometrical model we analyzed the displacement distribution and
its relation to the observed fault drag. Thereby, we demonstrate that fault
drag is a valuable additional criterion to constrain the evolution of large
normal faults by the coalescence of initial segments.
The investigated area is located at the central part of Vienna basin (Fig
4-1a). This thin-skinned rhombohedral basin (Royden, 1985) covers 5000
km2 and has been extensively studied for hydrocarbon exploration (Wessely,
1988; Hamilton et al., 2000; Strauss et al., 2006; Fuchs and Hamilton,
2006; Hölzel et al., 2010) as well as for seismic activity (Decker, 2005;
Hinsch, et al., 2005a).
The Vienna basin is characterized by the three distinct stages of
evolution, whereby the investigated near-fault sequence belongs to the pull-
apart phase. The early basin formed in the lower Miocene (23 Ma) as a
result of the lateral escape of the Eastern Alps (Ratschbacher et al., 1991;
Peresson and Decker, 1997) along the Vienna Basin transfer fault whereby a
final foreland imbrication lasted up to the Karpathian stage (17 Ma)
(piggyback basin stage, Decker, 1996). The Early to Middle Miocene
stratigraphic cycle uncomfortably covered pre-Miocene Alpine-Carpathian
nappes whereby a successor left stepping en-échelon fault pattern was
4.2 Geological setting
Deformation around basin scale normal faults
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comprised of the NE-striking sinistral faults and NNE-striking normal faults.
Figure 4-1. (a) Tectonic sketch map of the Vienna basin (modified after Strauss et al., 2006),
(b) Position of the 3D seismic block Seyzamdue (OMV) near the Markgrafneusiedl fault that is
investigated in this study, and the two deep exploration boreholes Markgrafneusiedl 004 and
Gänserdorf Übertief 003a. Fault heaves from the structural map of the pre-Neogene basement
(modified after Kröll and Wessely,1993).
The most prominent Salzach-Ennstal-Mariazell-Puchberg fault (Linzer
et al., 2002) and accompanying structures delimited extensional duplexes
(Decker, 1996). During this pull-apart stage of basin evolution, (Fodor,
1995; Decker, 1996) horizontal extension enabled rapid subsidence of up to
1500mm/Ma (Hölzel et al., 2008), whereby normal faulting was induced by
lateral confinement of eastwards material removal (Peresson and Decker,
1997). Two depocenters were differentiated enabling sequence deposition
dating from the Badenian (~16 Ma) (e.g. Fodor, 1995) up to the Pannonian
age (8 Ma) (Hamilton et al., 2000).
The entire fault network (Fig 4-1b) of within Matzen-Schönkirchen gas
and oil field (Brix and Schultz, 1993) located within Vienna Basin is almost
Deformation around basin scale normal faults
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entirely known from 2D and 3D seismic data (Sauer et al., 1992). The
central Vienna Basin normal faults are kinematically linked to strike-slip
systems, whereby tectonic activity between Lower Sarmatian (13 Ma) and
Lower Pannonian (~ 11,5 Ma) produced thick hanging wall growth strata
that accompanied slip along normal faults (Hinsch et al., 2005b). However,
in contrast to this general trend of sediment accumulation observed in
sedimentary piles along the normal faults in the most of Vienna Basin, the
investigated Markgrafneusiedl normal fault does not exhibit a prominent
difference in the adjacent sediment thickness (Fig 4-2). Only a minor
difference in a near-fault thickness of the hanging wall and footwall seismic
record is observed below the top horizon h5 (Middle Pannonian). Therefore,
this exclusively normal fault with no evidence of strike-slip movement
(Beidinger, 2009) can be characterized by a lack of a prominent rollover.
Instead of a large-scale rollover anticline, the near fault strata record
reverse and normal drag structures with rather small and strongly variable
amplitudes. This observation is supported by the lack of evidence for a listric
fault geometry or a connection to a low angle detachment horizon at depth
in the seismic dataset (Fig 4-2b). Alternatively, a relation of the observed
folds to a reactivation of the fault with thrust kinematics is not documented
by any structural evidence in this area.
Using a combination of the seismic and borehole data, the investigated
Miocene depositional sequence is subdivided in several chronostratigraphic
domains illustrated by different amplitude geometries recorded within the 3D
seismic block. The sedimentary cycle begins with the limnic-fluvial Aderklaa
Formation comprised of conglomerates, sandstones and interbedded pelites
deposited on the pre-Neogene basement. After a change in the tectonic
regime, sedimentation started discordantly during the Early Badenian with
the deposition of the transgressive Aderklaa Conglomerate Formation
representing a braided river system (Weissenbäck, 1996). In the central
Vienna Basin the Badenian succession is characterized by distal and proximal
deltaic clastics and carbonates (Strauss et al., 2006). After a period of sea-
Deformation around basin scale normal faults
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level drop dated at the Badenian/Sarmatian boundary, a renewed
transgression in Sarmatian resulted in the deposition of marls and clays
within the central areas of the basin. In the subsequent Early to Middle
Pannonian period another transgression covered most of the Sarmatian
succession (Harzhauser et al., 2004) with a clayey and sandy lacustrine
sequence. The Middle Pannonian Formation Top is the highest section of the
seismic dataset that is chronostratigraphicaly constrained and is represented
by a similar clastic sequence.
4.3.1 3D seismic data from the Vienna Basin
The database used for this study is a high-resolution 3D seismic
survey located at the central part of Vienna Basin (Fig 4-1). The time-
migrated 3D seismic reflection dataset covers ~64 km2 with a recording time
of 4000 ms TWT (Two-Way-Traveltime; corresponding to about 7 km depth)
and has line spacing of 25m with ca. 30 m vertical resolution.
The seismic amplitudes provided satisfactory resolution of
morphological changes in map view, as well as in cross-sections enabling
high-resolution seismic images of the near-fault material (Fig 4-2). The
chronostratigraphic framework was constrained in an OMV in-house work by
calibration with numerous deep exploration boreholes. The five most
prominent, and continuously traceable seismic markers characterized by
distinctive high amplitudes were mapped in the 3D seismic cube, i.e. h1
(Lower Sarmatian), h2 (Lower Pannonian), h3 (Middle Pannonian), h4
4.3 Seismic dataset and analytical methods
Deformation around basin scale normal faults
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Figure 4-2. (a) The mapped horizon h3 (Middle Pannonian -20) within the 3D seismic block
indicated as the rectangle at Fig1b. Reverse drag of marker is clearly visible in hanging wall, but
also gently developed in the footwall of the Markgrafneusiedl fault. Map of the horizon h3 is
separated by the Markgrafneusiedl fault into the two seismic domains: hanging wall (SE) and
footwall (NW). (b) The seismic inline 344-1. The five most prominent seismic amplitudes as
stratigraphic markers were seismically constrained throughout the entire 3D cube volume: h1
Deformation around basin scale normal faults
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(Lower Sarmatian), h2 (Lower Pannonian), h3 (Middle Pannonian -20), h4 (Middle Pannonian -
12) and h5 (Middle Pannonian -5).
(Middle Pannonian) and h5 (Middle Pannonian). As the resolution of the
seismic data and the quality of the markers decreases significantly with
depth (roughly below 1300 ms TWT), our investigation is focused on the
sedimentary pile deposited from the top Lower Sarmatian up to Middle
Pannonian period (Fig 4-2b).
The 3D interpretation and fault mapping was based on detailed picking
of the aforementioned horizons in numerous inlines, crosslines and
additional lines roughly perpendicular to the fault strike using the seismic
interpretation software Landmark (GeoGraphix). Subsequently, horizon and
fault surfaces were generated in Gocad (Paradigm)by triangulation from the
mapped datapoints using preferably equilateral triangles. The elements of
the resulting 3D structural model mapped in TWT were subsequently
converted to depth using a formula proposed by Hinsch et al. (2005b),
assuming an exponential increase of the seismic velocity with depth in the
Miocene sedimentary succession due to an increase in compaction with
depth.
4.3.2 Generation of a structural model
The final 3D model contains a section approximately from 230 m down
to 2800 m of Markgrafneusiedl normal fault. The model was constructed by
using the 3D seismic data and information from the boreholes indicated in
Fig. 4-1b. The quality seismic data provided a traceable fault plane almost
down to the basement rocks (Fig 4-2), but unfortunately, reflections in a
vicinity of the lower fault tip are below seismic resolution. The highly
irregular seismic amplitude pattern in this lower section of the 3D block,
having a poor visual traceability is extremely difficult to map accurately. In
contrast, the central fault region contains abundant continuous subhorizontal
seismic amplitudes that are excellently traceable as stratigraphic horizons.
Deformation around basin scale normal faults
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Therefore, the interpretation that is restricted to the central fault section was
bracketed the investigated fault area between 280m to 1350m (Fig 4-3a).
Using this fault section, we analyzed the displacement distribution between
four hanging wall and footwall horizons, h2 up to h5. Displacement near
marginal markers records a sudden decrease that is actually an artifact
induced by a lack of traceable horizons. Therefore, in order to avoid
erroneous interpretation we disregarded displacement values adjacent to the
hanging wall of a boundary horizon h1, and above a footwall of the marker
h5.
In order to characterize the geometry of the fault surface and the
deformed horizons, we carefully analyzed five different attributes, i.e. fault
azimuth, fault dip, fault curvature, horizon dip and fault displacement within
the depth migrated structural model. For the visualization of the fault
topography, we calculated the Gaussian curvature (kG) across the entire
fault surface. The Gaussian curvature is the product of the minimum and
maximum curvature at a point. Cylindrical structures or flat planes have a
value of kG=0, while saddles have kG<0 and domes or basins kG>0 (e.g.
Mynatt et al., 2007; Lisle and Tomil, 2007). Areas wih kG≠0 represent
irregularities or corrugations in the fault surface probably associated with
older fault segments (e.g., Walsh et al., 1999; Mansfield and Cartwright,
2000; Marchal et al., 2003). Accordingly, areas with positive curvature are
convex to the hanging wall, and indicate areas of linkage, while areas with
negative curvature are concave to the hanging wall and represent former
segments (Lohr et al., 2008). In addition to fault curvature, dip and azimuth
are calculated from each of the equally sized, equilateral triangles of the
fault plane.
Once the fault morphology was constrained, the fault displacement
was calculated by using the five horizons listed above (h1 to h5). The 3D
fault displacement mapping is constructed in Gocad by defining the upper
and lower boundary of the horizons (cutoff lines) and subsequent
Deformation around basin scale normal faults
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computation of a midline between the cutoff lines. Finally, the fault surface
is color-coded with the throw information based on the constructed midline.
4.4.1 Geometric features of the fault surface
Geometric features of the fault surface were analyzed to identify
heterogeneities, and were subsequently correlated with the distribution of
displacement along the fault surface, calculated from the five investigated
horizons. For these analyses, only the central section of the investigated
fault was considered, which shows the most prominent and thus best
interpretable geometrical variations (Fig 4-3a).
Fault azimuth and dip
The average azimuth of the investigated section of the fault lies
around 40-65° whereby areas displaying the dominating azimuth can be
summarized as Region 1 (Fig 4-3b). However, there are several areas with
deviating azimuth values oriented roughly parallel to the fault dip, which
separate these areas of homogeneously average azimuth values. These
localized deviations roughly correlate with the areas of highest dip values
>60° (Fig 4-3c). The area marked as Region 2 comprises two subparallel
zones of higher (to the SE) and lower (to the NW) azimuth than average,
and corresponding high and low dip angles.
Fault curvature
The values of Gaussian curvature are highly variable across the fault
surface (Fig. 4-3d). Zones with zero curvature are elongated roughly parallel
to the fault dip, and represent cylindrical corrugations along the fault plane.
These cylindrical areas are interrupted by zones of negative curvature, which
4.4 Geometrical analysis of fault plane and marker horizons
Deformation around basin scale normal faults
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are interpreted as former fault segments. The maximum negative curvature
values are located at former segment tips. The linkage zones between these
Figure 4-3. (a) Oblique-frontal view to the 3D modeled surface of the investigated part of the
Markgrafneusiedl fault, including the position of the section analyzed in detail in (b-f). Fault
attribute maps: (b) Dip direction (azimuth) map, (c) Dip map, (d) Gaussian curvature map,(e)
Deformation around basin scale normal faults
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Displacement map, (f) Cross plot of dip and displacement map. See the main text for a detailed
explanation.
initial segments are characterized by positive curvature values. Zones
comprising high dip are in good correlation with zones of negative Gaussian
curvature, i.e. the assumed fault segments. In contrast, a correlative
mixture of high and low dip angle sections characterizes the linkage zones or
areas of positive Gaussian curvature. Generally, all of these structural
features are aligned parallel to the fault dip, suggesting the evolution of the
fault plane from a train of small, vertically elongated fault segments, which
at a later stage linked to form a common fault plane. On a larger scale,
Region 2 is highlighted by azimuth, dip and curvature values deviating from
the mean values, and can thus be interpreted as a linkage zone between two
earlier, large but geometrically poorly detectable segments (i.e. the two
areas marked as Region 1 and separated by Region 2). Dip values ranging
around 40° and less (green and yellow areas delimited by a red line in Fig 4-
3c) distributed as a “belt of localized dip islands” seems to have a delimiting
role of the upper section of a Region 1. This observation is underpinned by
areas of low negative curvature (yellowish-green areas on the Fig 4-3d
parallel to section boundaries) and thus this irregular discrepancy can
represent a vertical contact of the two earlier poorly recognizable large
segments.
Fault displacement
Similar to the previously investigated geometrical attributes, the
displacement distribution contoured on the fault surface also gives an
irregular pattern (Fig. 4-3e). Zones lining the top and bottom of the
investigated fault section are artifacts, which result from the lack of
traceable horizons above and below these depths. The displacement
distribution map indicates two prominent areas of displacement maxima
(~400 m and 480 m), which are elongated roughly along the fault strike.
These zones are interrupted by several local minima with only 150 - 200 m
Deformation around basin scale normal faults
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of displacement, aligned as a string of elliptical contours at two distinct
depth levels. The transition between the maxima and the local minima are
marked by steep displacement gradients. Generally, the NE part of the
investigated fault section displays larger areas of high displacement, while
the SW part, especially in the upper half of the fault, shows by trend lower
displacement values. The transition between these zones occurs roughly at
the center of the investigated fault section.
Fault displacement-distance plots and relation to fault dip
The overlapped dip and displacement contour-attribute map (Fig 4-3f)
discloses the fact that the areas of steep displacement gradient (narrow area
between highest and lower displacement) are represented by slightly higher
dip values (>60°) than the displacement maxima itself. Generally, the dip
values of the investigated triangles range between 28 and 76° (Fig 4-4a),
displaying roughly a normal distribution with a mean around 51°. To analyze
the relation between dip and maximum displacement, we plot the extracted
dip values against the maximum displacement of the corresponding area.
The results indicate a correlation between fault dip and displacement (Fig 4-
4b), whereby fault sections of 30-40° dip correlate with a maximum
displacement of ~280 m, whereas the sections of 40-44° have significantly
higher maxima of 400 m. At last, sections with the steepest dip angles of
45-50° are characterized by maximum displacement values of up to 480 m.
A vertical displacement value is actually a 3D vector value measured
between two separated points at the intersection between of the marker in
the hanging wall and footwall. In both vertical displacement profiles,
displacement is measured exclusively along the investigated fault section
(indicated in Fig. 4-3a), and is not measured from the actual fault tips due
to the lack of reliable horizons.
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Figure 4-4. (a) Histogram of the dip attribute map. (b) The dip-displacement point-based
diagram illustrates the relation between maximal displacement and dip angle. Fault sections
between 30°-40° have a maximum displacement of ~280m, whereas the sections of (ii) 40°-
45° have the maxima of 400m and finally the sections of (iii) 45-50° are characterized by max
values of 480m.
Deformation around basin scale normal faults
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Figure 4-5. Displacement-distance plots (a, c) of two sections (A and B, marked in Fig. 3e)
recorded along the dip direction of the Markgrafneusiedl fault, and the corresponding dip-
displacement profiles (b, d). The maximum displacement measured along both sections varies
between 200 and 425 m. The displacement maxima are separated by the several minima,
whereby a general increase in displacement downwards can be observed. Both in displacement
and in dip-distance diagrams, sections with a similar dip are marked. Changes in dip angles
commonly correlate with changes in displacement along the fault.
The profiles A and B exhibit three prominent maxima that are
separated by the two minima in Sections A and B, whereby a general
increase in displacement is observed downwards i.e. towards the deeper
fault sections (Fig 4-5a and 4-5c). The fault dip-distance plots (Fig 4-5b and
4-5d allow a distinction of vertical sections comprised of areas with a similar
dip, whereby sudden variations in dip angle point to the existence of a
segment boundary.
4.4.2 Geometric features of marker horizons
Variation of reverse and normal fault drag along dip and
strike of the fault
The 3D structural model reveals a complicated pattern of antiform-
synform folding (‘antiform-synform fold train’, Grasemann et al, 2003)
developed in both hanging wall and footwall domains (Fig 4-6a-e).
Within the hanging wall, the deepest reliable horizon h2 illustrates the
lowest structural section of the investigated fault part, approximately at the
center of the Markgrafneusiedl fault. In the 3D perspective view of the
horizon color-coded for depth, three distinctive features of relatively high-
amplitude-wavelength reverse drag structures - R1, R2 and R3 - are
developed (Fig 4-6b, yellow colored sections of the marker h2). Each reverse
drag structure is separated by a similar amplitude normal drag - N1, N2, N3
Deformation around basin scale normal faults
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- whereby N3 has significantly larger amplitude (Fig 4-6b, light red colored
sections of the marker h2).
Figure 4-6. (a) Oblique view on the 3D modeled reverse and normal drag developed within the
footwall and hanging wall of the Markgrafneusiedl fault. The sections of the 3D model
illustrated the different amplitudes reverse and normal drags distributed within the hanging wall
Deformation around basin scale normal faults
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tracked from a bottom towards a higher fault domain: (b) marker h2, (c) marker h3, (d) marker
h4, (e) marker h5. (f)-(h) Contact between the marker h3 and the fault, associating the fault
attributes (dip, curvature and displacement) with the fault drag geometry (g) additionally
displays the more gentle, large scale reverse and normal drag superposed onto the smaller
scale features . i) Dip of the marker horizon recorded along the fault strike varies between 0
and 27° (location of the profile marked in (h)), illustrating alternating reverse and normal drag
along the fault.
The fault drag amplitude is represented by the maximum curvature of
a particular fold measured from the zero Gaussian curvature contour (Fig 4-
6b-e, approximation of zero curvature represented in black lines). The
distribution of the fault drag structures with a different sense within the
footwall (Fig. 4-6a) is complementary with the hanging wall fault drag array,
however, unlike the high drag amplitudes recorded within the hanging wall,
the footwall amplitudes are significantly lower but still are visible and
mathematically measurable. For example the footwall normal drag N1’ (Fig
4-6a) juxtaposed to N1 with 24m of amplitude has only a magnitude of ~6
m. Difference in fault drag volumes can be explained by several reasons (for
a detailed explanation see chapter 5.4.). In order to illustrate the
relationship between fault segments and fault drag, omitting uncertain
footwall drag amplitude discussion, we confined the investigation on the
well-developed drag structures in the hanging wall. In contrast to the
previously described three prominent reverse drags (R1, R2 and R3), the
most prominent feature is a large-scale normal drag (N3), which is
developed in all of the four investigated horizons (Fig. 4-6b-e). Large normal
drag is associated to the adjacent Region 2 of the fault surface. This high-
amplitude, downwards deflected hanging wall feature clearly separates the
central region of all markers from the surrounding large positively upwards-
deflected host rock material (Fig 4-6b, ‘generalized drag geometry’).
In the next investigated horizon h3, ca. 100 m above h2, the
magnitude of the locally developed reverse drags R1, R2 and R3 slightly
decreases (Fig 4-6c). The two reverse drag features R2 and R3 that are
Deformation around basin scale normal faults
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developed near the large-scale normal drag N3 are coalesced, and are here
represented by a single reverse drag (R2+3). A decrease in amplitude,
including a modification of the drag sense and coalescence of the two
neighboring drag features (R2 and R3) are in accordance with the local
distribution of displacement along the fault plane.
In the upper fault sections (horizon h4, Fig 4-6d), the amplitude of
reverse drag including the amplitude of large-scale normal drag record a
general decrease. The reverse drag features accommodated across the
Region 1 dominate the horizon geometry in comparison to normal drag,
whereby the large central marker depression (N3) also records a volume
drop. R1 and R2 form a single reverse drag structure (R1+2) with two local
maxima but with a negligible interruption by, compare to the distinct N1
feature observed in the horizons below and above. In contrast, N2 is well
developed between R3 and the R1+2 structures. A decrease of the h4
marker amplitudes is most likely associated with a decrease of the finite
displacement that is related to the proximity of fault tips (large upper
contact of Region 1, red line in Fig 4-3c).
A similar situation can be observed across the shallowest horizon h5
(Fig 4-6e), where the drag amplitude and the finite offset further decreases.
However, R1, N1, R2, N2, R3 and N3 can be still discriminated.
Correlation between fault drag and fault attributes
In order to examine the correlation between fault drag and other fault
attributes, we focus on the drag geometries of horizon h3 (Fig 4-6f, g and
h), analyzing the drag features from left to right along the fault. The R1
substructure is a well developed reverse drag antiform, which is related to a
negative Gaussian curvature (Fig 4-6f) as well as a local displacement
maximum of ~400 m (Fig. 4-6g) and moderate fault dip values (Fig. 4-6h).
In summary, these observations suggest that the location of R1 represents
an initial fault segment.
Deformation around basin scale normal faults
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The neighboring normal drag N1 is spatially restricted between the two
well-developed reverse drags, R1 and R2+3. N1 is developed around a field
of positive Gaussian curvature, suggesting a position at a local transfer or tip
zone. Additionally, both small displacement values, as well as high dip
values in this area contribute to this assumption.
The R2+3 represents the locally developed fault drag cluster
comprised of three distinguishable amplitude maxima (R2+3a ~ 42 m,
R2+3b ~ 21 m, R2+3c ~ 31 m). Along the fault plane, R2+3 is associated
with the vertical contact between zones of positive and negative curvature
(Fig 4-6f), moderate to high dip values (Fig. 4-6h). The position of R2+3a,
which shows the highest amplitude within this cluster of reverse drag, fits
perfectly to a high displacement field of ~400 m (Fig 4-6g) The decrease in
drag amplitude of R2+3b and R2+3c is related to a decrease in displacement
and a zone of negative curvature, probably indicating a later generation
relative to R2+3a ,and subsequent coalescence of the two segments.
Further to the right, the amplitude of R2+3 decreases, where
eventually the entire reverse drag cluster changes amplitude sign and
transits into the large single normal drag (N3). The occurrence of N3 is
related to the Region 2 where additionally the displacement maximum of the
investigated fault section is located (Fig. 4-6g). The displacement maxima
are accompanied by a large normal drag (instead of large reverse drag)
comprised of no substructures, we assume that the growth of the N3 is a
result of a single propagation event associated with this presumably overlap
zone (henceforth F3) between the fault tips of morphologically almost
undetectable two large segments (henceforth F1 and F2).
The 3D structural model illustrates the geometrical properties of fault
drag emphasizing a significant difference in amplitude between the R1, N1,
R2, N2 with respect to the N3. By quantifying amplitude variations, a link
between localized fault drag cluster represented by R1, N1, R2, N2 and the
Deformation around basin scale normal faults
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two larger reverse drag structures, separated by N3 (Fig 4-6b, ‘generalized
drag geometry’) can be constrained.
4.4.3 Interpretation of fault architecture
The quantification of fault drag across the horizons h2-h5 clearly
indentifies the initial fault segments, however using a fault morphological
analysis, the linkage of initial segments resulting in the formation of F1 and
F2 is rather unclear.
Linkage or overlap zones are characterized by a distinctive morphology
of branch domains (branch lines) (e.g. Walsh et al, 1999). These zones are
actually a result of progressive replacement of fault tips during development
of linkage zones. Kinematically, the overlapping fault zones can be
characterized by a steepening and positioning of the maximum slip that is
localized near or inside relay zones (e.g. Peacock and Sanderson, 1991;
Marshal et al., 2003).
Fault segment F3 which contains two displacement maxima (Fig. 4-3e)
is characterized by a distinctive morphology of overlapping zones (azimuth
map, Fig 4-3b) (e.g. Walsh et al, 1999). In addition to these two indicative
features of the F3, in the adjacent marker horizons a large normal drag (N3)
is developed. This discrepancy can be interpreted as a sign for a secondary
or late propagation between the two large faults (e.g Rykkelid and Fossen.,
2002) therefore suggesting that the Region 1 is actually divided on two
faults (F1 and F2). Confirmation of such spatial arrangement comes from the
fact that F1 and F2 already accumulated displacement and caused reverse
drag formation in the adjacent markers. Once a thoroughgoing fault surface
between F1 and F2 was established, the maximum displacement was
accumulated in this central area of the fault, but no reverse drag could be
generated due to a lack of displacement gradient. The observed N3 normal
drag geometry along F3 is thus interpreted as an inherited feature, which
formed at the lateral tips of the early F1 and F2 fault segments.
Deformation around basin scale normal faults
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The structural model of the Markgrafneusiedl fault surface shows the
complex morphology of the fault surface and heterogeneous displacement
patterns of marker horizons (Fig 4-6). In the following, we want to discuss
how geometric parameters are related to mechanical linkage of fault
segments and derive a growth history of the Markgrafneusiedl fault including
a prediction of the deformation in the footwall of the fault, which is usually
poorly constrained by 3D seismics.
4.5.1 Fault displacement and morphology as criterions for
segmented faults
The fundamental geometric values that can help to differentiate
models of formation of a fault zone or fault array are parameters that
identify individual fault segments that may link during fault growth (Walsh et
al., 2003). Displacement distribution of faults may help to identify
mechanically individual segments from segments that are mechanically hard
or soft linked (Fig 2 of Walsh et al., 2003). However, in highly complex large
fault zones where fault tips are not exposed in the investigated section,
simple displacement – distance analyses may result in rather ambiguous or
unclear results. The along-strike displacement – distance profile of the
Markgrafneusiedl fault segment (Fig 4-7b and 4-7c) records variations in
displacements that are not always directly related to fault segments.
4.5 Discussion
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Figure 4-7. (a) Schematic map (top view) and (b) the Gaussian curvature 3D map of the fault
plane (oblique view), where two large, slightly overlapping fault segments (F1 and F2) are
connected by a relay fault (F3). The presumably older segments F1 and F2 show a reverse drag
of the adjacent markers on a large scale (see Fig.6cand 6g), while the relay fault F3 is related
to markers with a normal drag. (c) Correlation of the 3D displacement attribute map with the
Deformation around basin scale normal faults
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along strike throw-distance plot (d) Schematic sketch of the relay zone between F1 and F2
breached by the relay fault F3.
The most illustrative section of a displacement profile that might cause
an ambiguous interpretation is associated to the section near the F3, where
a low displacement zone (tip zone between two segments) should be
expected. Surprisingly, this section is characterized by the maximum finite
displacement because the inherited tips are connected by the relay fault F3
(Fig 4-7c and 4-7d). Therefore, the linkage and subsequent displacement
migration may cause an abrupt finite displacement increase. Such
asymmetric slip distributions and/or multiple slip maxima on normal faults
may be the result of linkage of individual fault segments or may reflect
mechanical interaction between intersecting faults (Peacock and Sanderson,
1996) that produce local perturbations of the stress field resolved on the
faults (Maerten et al., 1999). Numerical elastic models demonstrate that
multiple slip maxima forced by intersecting faults are not located along the
intersections, nor at the fault centers. Therefore, the use of displacement
distance plots alone are of limited practical use for the detection of fault
segments, especially around such complicated large faults.
In order to increase the limited information of slip distributions along
faults, other studies combined analysis of the 3D geometry of segmented
faults with displacement asymmetry measurements (e.g. Childs et al., 2003;
Lohr et al., 2008). Analyzing a synsedimentary fault, Childs et al., (2003)
constructed the varying throw contour patterns on the strike fault
projections demonstrating that the locations of fault maximum and minimum
fields indicated local growth directions. Lohr et al., (2008) combined 3D fault
morphology data with displacement distance graphs, suggesting that the
fault segmentation is reflected by triangular to half elliptical shaped real
displacement profiles superimposed to the 3D fault segmentation pattern. By
using true displacement in along slip normal movement the authors
demonstrated significant differences in a real displacement, vertical and
Deformation around basin scale normal faults
101
horizontal displacements identifying the former fault segments. The authors
caution the use of throw values, which lead to a smoothing of the real
displacement curves. Displacement analyses along the Markgrafneusiedl
fault demonstrate that results of both techniques, the displacement distance
profiles (Fig 4-7c) and the 3D vertical displacement distance plot (Fig 4-5)
exhibited a series of local displacement maxima and minima that are weakly
correlative with adjacent segment centers or linkage zones.
The mechanical linking of differently sized segments can result in a
significant change of the inherited displacement pattern (Zee and Urai,
2005) and therefore analysis of the plot or 3D displacement attribute map of
the Markgrafneusiedl fault provided no satisfactory evidences supporting
individual segment boundaries delineation, propagation and eventual
linkage. Another difficulty in determining the hierarchy of factors that affect
the progressive change in displacement is expressed as a constant
propagation of local segments that are active even after larger segments
being linked. This mechanical interaction is caused by release of large strains
in the regions of segments contact (Dawers and Anders, 1994).
Many studies designated fault morphology and fault displacement
profiles as techniques that provide either influenced (e.g. Peacock and
Sanderson, 1996; Nicol, 1996, Bürgmann, 1994) or incomplete and unclear
picture of the possible initial fault segments (Lohr et al., 2008). However,
since the segmentation and fault linkage clearly influences the displacement
pattern along the fault (Maerten et al., 1999; Walsh et al., 2002) and since
displacement gradients generates fault drag, quantification of fault drag may
help to detect linked fault segments.
4.5.2 Fault drag as a criterion to identify fault segments
As a result of a fault slip, heterogeneous stress and displacement fields
develop in the surrounding rock (Pollard and Segall, 1987). Elastic theory
predict and some natural faults demonstrate that the displacement field
Deformation around basin scale normal faults
102
around an isolated fault is elliptical, reaching a maximum at the center of
the fault and dropping to zero at the fault tips (Rippon, 1985; Barnett et al.,
1987; Pollard and Segall, 1987; Walsh and Watterson, 1989). However, the
infinite displacement gradient at the fault tips may be significantly influenced
by changes in the frictional strength along a fault, spatial gradients in the
stress field, inelastic deformation near fault terminations and variations of
the elastic modulus of the host rock (Martel, 1997; Cowie and Shipton,
1998; Bürgmann et al., 1999).
The wavelength and the amplitude of fault drag is mainly a function of
size, the finite displacement and the displacement gradient of the fault
(Grasemann et al., 2005). Larger amplitude drags are facilitated by constant
wavelengths (e.g. confined faults) during increasing fault slip (Fig. 4-8a).
During fault segment linkage, different wavelength and amplitude of fault
drag may be superposed on inherited smaller wavelength and amplitude
drag geometries (Fig. 4-8b and 4-8c). Even the sense of the drag (e.g.
normal drag) may be inherited in a linked larger structure (e.g. reverse
drag).
Fault drag has been described and analyzed in natural examples at
various scales, as well as in analogue and numerical models (e.g. Barnett et
al., 1987; Passchier, 2001; Exner et al, 2004; Coelho et al., 2005;
Grasemann et al., 2005; Wiesmayr and Grasemann, 2005; Resor, 2008 and
Spahić et al., in press). The modeling results of drag around a single finite
fault plane predict different drag sense on a central marker line (reverse or
normal) as a function of the orientation of the marker line with the fault.
Importantly, the magnitude but also the sense of drag must change on
Deformation around basin scale normal faults
103
Figure 4-8. Normalized fault (segment) length – fault drag amplitude diagram illustrating the
mechanism of progressive fault drag amplitude development (top view). Initially growth of
isolated non-restricted fault segment presented has symmetry in fault length and drag
amplitude (stage 1). Subsequently after segment tips being restricted, an amplitude increase is
likely to occur (stage 2 and 3). (b) Schematic growth model and coalescence of two different
laterally juxtaposed fault segments with the similar amplitudes. After segments have coalesced,
a relic of normal drag remained. (c) A schematic growth model of final large-scale fault surface
accompanied by the overall reverse fault drag that records a slight amplitude increase. The
overall drag geometry is disturbed by the continuous propagation of local segments.
Deformation around basin scale normal faults
104
marker horizons, which do not meet the center of the fault, in order to
maintain strain compatibility (Grasemann et al., 2005). Consequently, a
smaller wavelength/amplitude drag may change its sense during fault
propagation and/or linkage because the relative position of the marker with
respect to the center of the fault has changed.
An excellent example of inherited drag is preserved in the horizons h2-
h5 along the Markgrafneusiedl fault (Fig. 4-6), where the association of
reverse and normal drag (anti- and synforms) may represent earlier
individual fault segments that finally linked by the fault segment F1.
The suggested growth history of the Markgrafneusiedl fault is not
intuitive from the displacement and morphology analysis of the fault alone
because of the heterogeneous displacement gradient superposition due to
fault linkage By including in our investigations the mapping of drag along the
marker horizons, we present in the following a suggested growth history for
the Markgrafneusiedl fault (Fig 4-9).
4.5.3 Evolution of the Markgrafneusiedl fault
The investigated section of the Markgrafneusiedl fault dating from the
Lower Sarmatian up to almost Middle Pannonian time evolved in three
distinctive growth phases. We assume that the Markgrafneusiedl fault
propagated progressively towards the today tip zones since the fault
dimensions and displacement values display a general decrease towards the
fault tips.
The nucleation of the discontinuity was most likely induced by the
activity of a precursor fault embedded in a pre-Neogene basement (see Kröll
and Wessely, 2000). Locally distributed and isolated fault planes of similar
size generated fault drag structures in the adjacent sedimentary horizons
(Fig 4-9a). A maximum age of the initial propagation phase is the Lower
Pannonian (~11 Ma), since the oldest fault drag is observed in the horizon
Deformation around basin scale normal faults
105
h3.
Figure 4-9. A schematic illustration of the evolution of a Markgrafneusiedl fault (left, oblique 3D
view on schematic reconstruction; right, schematic cross-section): (a) isolated small fault
Deformation around basin scale normal faults
106
segments produce reverse fault drag in the adjacent marker horizons; (b) propagation and
linkage of initial localized segments towards the larger fault segments F1 and F2 which are also
associated with a larger reverse drag (c) relay fault F3 breaches the overlap between the large
segments, and generates normal drag geometries in the adjacent marker horizons (d)
schematic cross-section illustrating the prediction technique of a not-displaced (1a and 1b) and
displaced reverse drag in a far fault deformation field (1a’). The technique of prediction is
described in text.
After the vertically elongated faults have linked (Fig 4-9b), the
successive deformation phase was characterized by a new enlarged, but still
separated displacement field associated to the newly generated larger fault
segments F1 and F2. The new resulting perturbation strain induced
mechanical interaction between two segment generation, resulting in a
localized mild obliteration of the inherited drag amplitude pattern unraveled
by the minor amplitude fluctuations within the R2+3. Finally, lateral
bifurcation of the fault tips of faults F1 and F2 ended in a linkage leaving a
single normal large drag (N3) that accompanies propagation of this overlap
(Fig. 4-9c). The volume of N3 records a progressive drop directed towards
the higher fault sections (from h2 towards h5), whereby significant decrease
is associated to Middle Pannonian, in a time between the markers h4 and h5.
Additionally, the h5 illustrated lowest or zero amplitude of N3, corroborating
suggestions that the linkage of F1 and F2 was before h5. This once
propagating relay zone evolved in a typical geometry that characterizes
relay faults (‘completely breached relay zones’ (Marchal et al., 2003, Fig.16-
6). After the relay zone was breached, the spatial restriction of the new fault
F3 disabled further lateral propagation, enabling accumulation of larger
strains (Ackermann et al., 2001). Thus, the largest finite displacement
values are associated to the today’s central fault section that is tapered
around the segment F3.
Including fault drag into the standard investigations of fault evolution,
a growth history of a Markgrafneusiedl fault zone has been suggested. In the
following, we use the same technique in order to predict the footwall
Deformation around basin scale normal faults
107
geometry of the Markgrafneusiedl fault, which is less well constrained by 3D
seismics than the horizons in the hanging wall.
4.5.4 Footwall geometry prediction
Deformation in the footwall is frequently observed in outcrops and
seismic data (Kasahara, 1981; McConnell et al., 1997; Mansfield and
Cartwright, 2000) but hanging wall deformation is much better constrained
in structural models of faults (Tearpock and Bishke, 2003) because of
following reasons. Firstly, displacements due to a drag effect in the footwall
can be less intensive than those in the hanging wall, especially when inclined
faults interact with the earth surface (Grasemann et al., 2005). However,
footwall deformation along near surface faults provides a strong evidence
that the fault has a displacement gradient (e.g. Spahić et al., in press).
Secondly, the resolution of 3D seismic record near a fault plane may
frequently result in a much higher resolution within a hanging wall (Tearpock
and Bischke, 2005) whereby a footwall record is often obscured or can have
poor seismic resolution (e.g. compare lower structural levels of the footwall
in Fig 4-2b). Furthermore, it has been shown that flattening normal faults
are disappearing in the seismic data with increasing depth (e.g. Tearpock
and Bischke, 2003). Listric fault models (e.g. McClay et al., 1990) have been
frequently used to define a structural model for hydrocarbon exploration
near large normal faults. Since many of these models are based upon the
assumption that the footwall below the fault surface behaves as a rigid body
(e.g. Yamada and McClay, 2003), the petroleum targets are mainly confined
to the hanging wall anticlines. In contrast to the listric model predictions,
against the commonly observed hanging wall reverse drag assets above a
finite normal fault, (e.g. Porras et al., 2002) an additional hydrocarbon
reservoir could be expected within footwall synclines. Unfortunately, as
described above, in contrast to hanging wall domains, very often
deformations along a footwall of large non-vertical normal faults that record
Deformation around basin scale normal faults
108
a plane dip have deteriorated seismic resolution due to a reduced rate of
propagating seismic waves through a fault plane.
In order to predict the footwall drag shape and more importantly the
position of a contact with adjacent fault plane (cutoff), the two key factors,
hanging wall fault drag amplitude and the position of fault tips needs to be
constrained beforehand. Surprisingly, disarrangement between the footwall
and hanging wall amplitudes (e.g. Fig 4-6a) induced by an unequal fault slip
ratio has a minimized effect on prediction of the position of a footwall
reverse drag (see Fig 4-6a).
According to the elastic analytical solutions (Pollard and Segall, 1987)
both reverse and normal fault drag develops around planar fault segments
(Grasemann et al, 2005), whereby reverse drag refers to the markers that
are concave in the direction of a fault slip. (e.g. Fig. 4-9c, markers 1a, 1b
and 2). According to the model, the highest amplitudes of the hanging wall
reverse drag are associated to central fault sections. Taking this relationship
into account, the here exhibited footwall prediction technique is based upon
this central and near-central markers that are associated to the fault
sections characterized by highest displacement (Fig 4-9c and 4-9d markers
1a and 1b). In order to facilitate a footwall prediction technique that can be
also applied in the case of a segmented fault, in further text will be regarded
complicated deformation pattern of after-segments linkage (Fig 4-9c, Stage
3). Since displacement gradually decreases away from the central fault
section towards the tips, causing contemporaneous reverse drag amplitude
decrease, eventually in the proximity of fault tips reverse drag abruptly
transits to a normal drag (Fig 4-9c, stage 3 thinner pale black lines). As a
consequence, the along slip fault drag amplitude migrates and changes drag
sense, hence variations in drag amplitude indicate the position of fault tips,
which might be very useful for discriminating inherited tips among linked
segments (Wiesmary and Grasemann, 2005).
Deformation around basin scale normal faults
109
Once the position of fault tips is identified, another important issue is
the structural level of the footwall drag, i.e. determining if the marker
displays is an offset in the far field. If the investigated marker is not
displaced in a far fault field (e.g. markers 1a and 1b at Fig 4-9d), the
geometry of the assumed central marker in the hanging wall can simply be
mirrored in the footwall whereby according to the same elastic model of
Grasemann et al. (2005), the footwall geometry has exactly the same shape
as the hanging wall anticline.
However, very often a hanging wall marker is displaced in subsequent
deformation phase resulting in a downwards directed slip of the hanging wall
(e.g. marker h2, Fig 2b). Similarly, the prediction of displaced footwall
marker geometry can be achieved by mirroring of the hanging wall marker
(Fig 9d, marker 1a’) at the level of the corresponding chronostratigraphic
horizon in the footwall (1b in Fig 9d).
In summary, a detailed structural investigation of reverse and normal
drag in the hanging wall of a normal fault may not only identify hydrocarbon
traps in the hanging wall, but may be used to extrapolate footwall drag
geometries which commonly remain unexplored for hydrocarbon reservoirs.
The presented structural model mapped from a 3D seismic of the
Markgrafneusiedl natural fault in the Vienna basin focuses on near-fault
deformations of marker horizons in the hanging wall of the fault. Using this
additional information to conventional displacement distance plots and fault
morphology, we conclude:
(1) Fault drag is the near-fault feature that can occur at basin scale.
(2) Including fault drag into the established methods of fault analysis
(fault morphology and displacement) gives additional information on initial
segmentation and segment linkage during fault growth.
4.6 Conclusions
Deformation around basin scale normal faults
110
(3) Fault segments and fault drag are scale-dependent, whereby large
segments consisted of linked local faults are accompanied by similar size
fault drag that is comprised of local drag substructures. Around propagating
fault tips, a normal drag may develop, however unlike drag around segment
centers, drag originating from a tip propagation contains no substructures.
Therefore, such fault drag hierarchy can promptly disclose parent and
overlapping fault segments.
(4) Investigation of fault drag allows prediction of the geometry and
position of footwall horizons, which may record only bad signal in 3D
seismics. Syncline geometry characterized for a footwall drag can expand
the hydrocarbon exploration on below-fault blurred seismic domains.
(5) The investigation results clearly warned that not always, an
intuitive, shuffle-shaped fault surface comprised of relatively mild dip values
necessarily leads towards the listric fault model, but requires more detailed
morphological, kinematical and near-fault deformation analyses.
AAcckknnoowwlleeddggeemmeennttss
This study was funded by the Austrian Science Fund (FWF-Project
P20092-N10). We thank OMV EP Austria for providing the 3D seismic block
along with datasets from neighboring boreholes, and we appreciate
discussion on the specifics of this fault with P. Strauss and A. Beidinger.
Deformation around basin scale normal faults
111
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Austria. In: Royden LH, Horváth F (eds), AAPG Bull, 45, 333–346.
Wiesmayr, G., Grasemann, B. (2005), Sense and non-sense of shear
in flanking structures with layer-parallel shortening: implications for fault
related folds, J. of Struct.Geol., 27, 249–264.
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Yamada, Y., McClay K. (2003), Application of geometric models to
inverted listric fault systems in sandbox experiments. Paper 1: 2D hanging
wall deformation and section restoration, J. of Struct. Geol., 25, 1551–1560.
Zee, W. v.-d., Urai, J.L. (2005), Processes of normal fault evolution in
a siliciclastic sequence: a case study from Miri, Sarawak, Malaysia, J. of
Struct.Geol., 27, 2281-2300.
Deformation around basin scale normal faults
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5. Synthesis: importance of fault drag criterion in
assessment of fault surface geometry and
segmented pattern
Deformation around basin scale normal faults
120
The correct interpretation and recognition of faults and associated near
field deformations, i.e. fault drag, are fundamental for a comprehensive
reconstruction of the kinematics and history of fault propagation. Based on
balancing methods and 3D visualization of natural fault and fault drag
structures that are presented in this thesis, the importance of near fault
deformation around planar discontinuities is stressed out and several new
insights are obtained.
5.1.1 Significance of 3D structural modeling
The understanding of processes, which are linked to deformations in
the Earth's crust, various balancing techniques as well as scales analogue
models provide best visualization tools subsequently used for physical
models. Such structural quantifications need as many quantitative
constraints for the setup of appropriate models as possible. One major group
of important input data is the spatial geometry of geological surface and
subsurface structures.
Using 3D modeling, we spatially visualized the relation between two
different types of structures (e.g. Fig 6-1), which is very often only
detectable partially in cross sections (fault traces and profile of fault drag).
Furthermore 3D visualization is a proven tool to detect relations between
different data sets, which otherwise are hidden or unclear, e.g. fault traces
exposed on outcrop and 3D spatial visualization of same traces behind an
outcrop.
Data examples and resulting interpretations are discussed in the frame
of existing models of the Vienna Basin system focusing on some important
5.1 General conclusions
Deformation around basin scale normal faults
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differences between the Miocene meso- and large-scale fault and near-fault
deformation systems.
Fig.6-1. Oblique view of the depth migrated structural 3D model of the Markgrafneusiedl fault
and near-fault markers.
5.1.2 Reverse fault drag and geometrical fault models
Using a set of visualization (GPR and 3D seismic), modeling and
balancing methods, the large deflections of initially planar markers around
two regional normal faults is investigated. Initially, the resulting balanced
solution implicated that large-scale reverse drag structure has been
developed around the final length normal fault (Chapter 3). The application
of combination of field mapping, GPR, and depth-to-detachment balancing
method revealed:
(1) NO LISTRIC OR DOWNWARDS FLATTENED FAULT SECTION OR
SMALLER-SCALE DETACHMENT IS OBSERVED ALONG THE FAULT EXPOSED
ON GRAVEL PIT NEAR ST. MARGAREHTEN; NEITHER IS A WEAK
DETACHMENT (E.G. CLAY OR SALT LAYER) IN A LOWER STRUCTURAL
LEVEL OF THE NORMAL FAULT DISOCVERD, RESULTING IN A DISMISSAL
OF BOTH A LISTRIC FAULT SENSU STRICTU OR A TECTONIC RAFT
SYSTEM.
Deformation around basin scale normal faults
122
Subsequently the presented structural model mapped from a 3D
seismic block of the Markgrafneusiedl normal fault in the Vienna basin
(chapter 5) focuses on the deformation of marker horizons in the hanging
wall of the fault. Using this additional information to conventional
displacement distance plots and fault morphology, we conclude:
(2) THE INVESTIGATIONS OF DEFLECTED MARKER HORIZONS NEAR THE
IRREGULAR MARKGRAFNEUSIEDL FAULT SURFACE PROVE THAT FAULT
DRAG IS A FUNCTION OF A SINGLE PROPAGATING SEGMENTS AS WELL
AS FROM THEIR COALESCENCE AND SUBSEQUENT GROWTH
5.1.3 Fault drag as criterion to recognize fault segments
Investigation and identification of coalesced fault segments has been
commonly comprised of the displacement distribution analysis sometimes
combined with studies of fault morphology (e.g. Watterson, 1986; Barnett et
al., 1987; Walsh and Watterson, 1989; Cartwright et al, 1995; Contreras et
al., 2000; Kim and Sanderson, 2005; Marchal et al., 2003; Lohr et al.,
2008a). Although displacement analyses provide satisfactory results, very
often displacement-distance graphs exhibit ambiguous disturbed elliptical
shape (Nicol et al, 1996).
The basic principles of geometrical fault drag analysis discussed in
Chapter 4 assume that fault drag is a function of each active fault segment
induced by displacement asymmetry. Therefore, the argument of the
aforementioned study is that quantification studies of fault drag can be used
as an additional tool in recognition of fault segments and importantly for
reconstruction of the overall fault evolution. Consequently, the investigations
of a planar-segmented mature fault that records a displacement gradient
revealed that the evolution of each segment can induce a local different
scale-dependent development of fault drag in the adjacent marker horizons.
Deciphering different origin of propagating fault segments by using a
combination of fault morphology and drag amplitude studies, it was
Deformation around basin scale normal faults
123
concluded that fault drag can help to distinguish parent from linkage or relay
faults.
5.1.4 Progressive evolution of segmented faults reconstructed by
fault drag amplitude criterion
The models that describe fault drag with segmented fault growth are
limited. The model of vertical segment propagation (Wiesmayr, 2005)
investigates the 2D distribution of fault drag around two finite length fault
segments. Reverse drag develops in the center of a fault segment whereby
normal drag is associated with segment tip zone. (Fig 4-10 in Wiesmayr,
2005).
Deformation around basin scale normal faults
124
Figure 6-2: 3-stage conceptual model based on flanking structure theory according to
Wiesmayr, 2005. a) Stage 1: Isolated flanking structures develop along planar fault segments,
fault tips remain stationary. b) Stage 2: Fault tips propagate and individual fault segments start
to link to form a segmented normal fault. c) Stage 3: Post-linkage fault displacement occurs
and forms fault drag superposition on shallow segments.
In chapter 5 the usefulness of the fault drag as a criterion to
characterize the evolution of segmented faults was analyzed. Linking the
study of drag magnitude, its evolution and role in segment linkage
emphasized the importance of this structural feature. The study has shown
how additional information can be gained from detailed structural mapping
of fault drag, which significantly extends the recognition of fault segments
from displacement-distance measurements and other geometrical
parameters of the fault surface.
5.2.1 Numerical modeling of propagating segments and
associated fault drag
Often natural examples of structural phenomena have been used to
confirm application and results of numerical analyses and theoretical results.
Despite the complex relationship between fault segmentation and fault drag
illustrated by the model of the Markgrafneusiedl fault, numerically computed
fault drag behavior during segment linkage could indicate development of
5.2 Presented solutions and future outlook
Deformation around basin scale normal faults
125
fault drag around local perturbations, depicting the mechanical behavior
during processes of segment propagation and subsequent linkage.
Analytical models of the instantaneous displacement field around an
isolated fault in an infinite elastic body predict that fault drag develops on
both sides of the fault (Grasemann et al., 2005). Theoretical displacement
field around a single dip-slip fault that reveal normal and reverse drag
develop due to a slip confirmed by the model predicting increase of drag
magnitudes toward the center of fault. Additionally, the angular relationship
between the fault surface and the adjacent layers is constrained, whereby
normal drag develops around low angle fault and reverse drag occurs around
a high angle fault.
Using constrains of the above analytical solution, numerical models
could capture fault drag amplitude development during fault propagation.
The investigation of perturbed fault-slip distributions with complex three-
dimensional geometries has been performed using the Boundary Element
Method (e.g. Maerten et al., 1999). The results could provide additional
constraints and confirm the proposed scenario of the development of the
segmented Markgrafneusiedl normal fault (Chapter 4).
5.2.2 Predicting possible weak zones near faults in hydrocarbon
reservoirs
Fractured reservoirs can be difficult to model and to exploit. The key to
a better understanding of sub-seismic structures lies in well data, but
commonly limited use is made of the vital data collected from core and
borehole images, even though these data provide the only direct information
about joints in hydrocarbon reservoirs. However, in the following the role of
fault drag in understanding of fracture distribution near hydrocarbon
reservoirs will be emphasized.
According to the inhomogeneous fault roughness, the rocks around the
fault should show an inhomogeneous strain field with high fracture
Deformation around basin scale normal faults
126
concentration in areas of strong fault undulations or high curvature (Lohr et
al., 2008a). Here, analyzed zones of high curvature are actually different-
scale small segment centers accompanied by reverse fault drag. These zones
of high curvature are affected by higher deformation in the surrounding
horizons induced by larger displacement along the fault, and therefore
should be characterized by a higher fracture density in these horizons
adjacent to the fault. Thus, a large segmented fault surface can exhibit a
variable fracture density in the adjacent host rock along both fault strike and
fault depth. From fault plane and fault drag analysis on the here studied
scale, it might be possible to make qualitative predictions about fracture
density around the major fault.
However, the influence of fault drag on a much smaller scale, e.g.
below the seismic resolution down to a few meters or even well data scale is
rather unexplored. Investigations of fault drag might help to localize strongly
fractured zones not visible in seismic data (e.g. Lohr et al., 2008b), which is
important for analyses of fluid migration and for reservoir characterization.
The complexity of the segmentation of a near-fault reservoir can lead
to the development of discrete fault blocks resulting in the
compartmentalization of a reservoir (e.g Freeman et al, 1998; Myers et al,
1998; Harris et al., 2003). Such geometrical complexity can cause a
significant stress variation across the hydrocarbon reservoir (Yale, 2003;
Morris and Ferrill, 2009; Maerten et al, 2002), and therefore a segmented
surface might affect fault sealing properties due to the development of
fracture zones (e.g. Aydin, 2000). Consequently, sealing efficiency (Harris et
al, 1998), trap integrity, and compartmentalization could be initially
illustrated by using a fault drag geometrical study in addition to analysis of
the fault surface geometry. The concept could be based on a fault
segmentation pattern adjacent to a hydrocarbon reservoir, whereby the
most important step is the delineation of the areas of a radical change in
segment orientation that can often represent local deformation zones
characterized by intensive fracturing (e.g Barr, 1998; Tearpock and Bischke,
Deformation around basin scale normal faults
127
2005; Aarland and Skjervena, 1998). These zones as a product of dominant
strain component accommodated by large faults (Lohr et al., 2008b)
additionally can be delineated by analyzing fault drag geometry. Using
intense changes in fault plane orientation frequently assigned as a transfer
or tip zone, which could be confirmed by the change from reverse to normal
drag along the fault plane, as shown on the example of the Markgrafneusiedl
fault (Fig 6-3).
Fig. 6-3. Oblique view on the 3D Markgrafneusiedl fault surface. (a) Gaussian curvature map
exposing the fault undulations; (b) Combination of the same 3D fault undulations with 3D fault
drag can delineate potential weak zones (black arrow).
Deformation around basin scale normal faults
128
References
Aarland, R. K., Skjerven, J. 1998. Fault and fracture characteristics of
a major fault zone in the northern North Sea: analysis of 3D seismic and
oriented cores in the Brage Field. In: Coward, M. P., Databan, T. S. &
Johnson, H. (eds) Structural Geology in Reservoir Characterization.
Geological Society, London, Special Publications 127, 209-229.
Aydin, A. 2000. Fracture, faults, and hydrocarbon entrapment,
migration and flow. Marine and Petroleum Geology 17, 797-814.
Barnett, J. A. M., Mortimer, J., Rippon, J.H., Walsh, J.J., Watterson, J.
. 1987. Displacement Geometry in the Volume Containing a Single Normal
Fault. American Association pf Petroleum Geologists B 71, 925-937.
Barr, D. 1998. Conductive faults and sealing fractures in the West Sole
gas fields, southern North Sea. In: Coward, M. P., Databan, T. S. & Johnson,
H. (eds) Structural Geology in Reservoir Characterization. Geological
Society, London, Special Publications 292, 431-451.
Cartwright, J. A., Trudgill, B.D, Mansfield C.S. 1995. Fault growth by
segments linkage: an explanation for scatter in maximum displacement and
trace lenth from the Canyonlands Grabens of SE Utah. Journal of Structural
Geology 17, 1319-1329.
Contreras, J., Anders, M.H., Scholz, C.H. 2000. Growth of a normal
fault system: observations from the Lake Malawi basin of the east African
rift. Journal of Structural Geology 22, 159-168.
Freeman, B., Yielding, D.T., Needham, D.T., Badley, M.E. 1998. Fault
seal prediction: the gouge ratio method In: Coward, M. P., Databan, T. S. &
Johnson, H. (eds) Structural Geology in Reservoir Characterization.
Geological Society, London, Special Publications 127, 209-229.
Grasemann, B., Martel, S., Passchier, C. 2005. Reverse and normal
drag along a fault. Journal of Structural Geology 27, 999-1010.
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Harris, S. D., McAllister, E., Knipe, R.J., Oding, N.E. 2003. Predicting
the three-dimensional population characteristics of fault zones: a sudy using
stochastic models. Journal of Structural Geology 25, 1281-1299.
Kim, Y.-S., Sanderson, D.J. 2005. The relationship between
displacement and length of faults: a review. Earth-Science Reviews 68, 317-
334.
Lohr, T., Krawczyk, C.M., Oncken, O., Tanner, D.C. 2008a. Evolution
of a fault surface from 3D attribute analysis and displacement
measuremants. Journal of Structural Geology 30, 690-700.
Lohr, T., Krawczyk C. M., Tanner, D., Samiee, R., Endres, H., Thierer,
P.O., Oncken, O., Trappe, H., Bachmann, R., Kukla, P. 2008b. Prediction of
subseismic faults and fractures: Integration of three-dimensional sismic
data, three-dimesnional retrodeformation, and well data on an example of
deformation around an inverted fault. AAPG Bulletin, V.92, 473-485.
Maeten, L., Gillespie, P., Pollard, D.D. 2002. Effects of locall stress
perturbation on secondary fault development. Journal of Structural Geology
24, 145-153.
Marchal, D., Guiraud, M., Rives, T. 2003. Geometric and morphologic
evolution of normal fault planes and traces from 2D to 4D. Journal of
Structural Geology 25, 135-158.
Myers, R. D., Allgood, A., Hjellbakk, A., Vrolijk, P., Breidis, N. 1998.
Testing fault transmissibility predictions in a strcuturally dominated
reservoir: Ringhorne field, Norway. In: Coward, M. P., Databan, T. S. &
Johnson, H. (eds) Structural Geology in Reservoir Characterization.
Geological Society, London, Special Publications 292, 271-294.
Nicol, A., Walsh, J.J., Watterson J., Breatn, P.G. 1995. Three-
dimensional geometry and growth of conjugate normal faults. Journal of
Structural Geology 17, 847-862.
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Tearpock, D. J., Bischke, R.E. 2003 Applied Subsurface Geological
Mapping. pp 821.
Walsh, J. J., Watterson, J. 1989. Displacement gradients on fault
surfaces. Journal of Structural Geology 11, 307-316.
Yale, D. 2003. Fault and stress magnitude controls on variations in the
orientation of in situ stress. From: Ameen, M. (ed.) Fracture and In-Situ
Stress Characterization of Hydrocarbon Reservoirs. Geological. Society,
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Deformation around basin scale normal faults
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6. Appendix 1
CURRICULUM VITAE
CURRICULUM VITAE – DARKO SPAHIĆ, STRUCTURAL GEOLOGIST (3D MODELER)
SUMMARY A geologist with almost 10 years of multidisciplinary geological experience collected in Algeria, Angola, Austria, Hungary, Italy, Libya, Serbia, Spain and Tunisia. Proven in applied subsurface research – and direct operational experience in both offshore & onshore operations: have conducted geological mud logging/wellsite geology and rig monitoring for vertical and horizontal wells. In general, along with a background in sequence stratigraphy, 3D geomodeling, field engineering, petrophysics, and expertise in structural geology, have relevant safety and petroleum industry trainings, excellent technical and IT abilities. As a proven team lead/player and innovative thinker, I have excellent communication abilities and presentation skills, fluent in English, German, Russian, and Italian. OBJECTIVE TO WORK AS A CONSULTANT GEOLOGIST (STRUCTURAL GEOLOGIST/3D MODELER).
ACADEMIC QUALIFICATIONS
October 2007- October 2010
PH.D. CANDIDATE in advanced structural geology, University of Vienna, Austria, Department for Geodynamics and Sedimentology . Geozentrum,, Althanstrasse 14, 1090, Vienna, Austria.
2001 – 2006 M.SC OR MAGISTER DIPLOMA in Tectonics/Structural Geology (hon.), University of Belgrade, Faculty of Mining and Geology, Department of Dynamic Geology/Tectonics. Djušina 7, 11000 Belgrade, Serbia.
1993 – 1999
GEOLOGICAL ENGINEERING DIPLOMA IN REGIONAL GEOLOGY (5 years). (hon.), (equivalent to Diploma in Geology/Paleontology according to Bologna Program) - University of Belgrade, Faculty of Mining and Geology, Department of Regional Geology and Paleontology. Djušina 7, 11000 Belgrade, Serbia.
CAREER HISTORY
October 2007 – October 2010:
RESEARCH ASSOCIATE at the Department for Structural Geology and Sedimentology, University of Vienna, Austria, engaged on Project: “Modeling of faults in various scales”. http://geologie.univie.ac.at/structural-processes-group/current-projects/natural-fault-geometries/
Sept 2004 to September 2007:
ASSISTANT OF CHIEF OF GEOLOGICAL DEPARTMENT, Geological Survey of Serbia and International Research Center, Tripoli, Libya. Surface mapping/exploration of the Sirte Basin (Libya) contracted as Structural Geologist, Senior Mapping Geologist (Sheet Coeditor) and Arc GIS specialist.
July 2002 to August 2004:
Geoservices International, Paris, France. http://www.geoservices.com GEOLOGICAL DATA ENGINEER - Angola: Cabinda deep off-shore, Semisub Sedneth 701, client Chevron-Texaco, 12/2003 – 08/2004. SENIOR LOGGING GEOLOGIST – Algeria, Hassi Messaoud, El Merk North….client Groupment Berkine Anadarko, 11/2002-12/2003. Logging Geologist – Italy on-shore: Villa d`Agri, client Agip, 09/2002-11/2002.
June 2001 to June 2002:
RESEARCH & TEACHING ASSISTANT, Faculty of Mining & Geology, Belgrade, Department for Geological mapping. Structural geologist interpretation of 2-D seismic sections (Drmno Project, southern Pannonian Basin, Serbia and Serbo-Macedonian Unit); http://www.rgf.bg.ac.rs/
WORK SKILLS STRUCTURAL & PETROLEUM GEOLOGY WELLSITE GEOLOGY INFORMATION TECHNOLOGY BUSINESS
• Structural Interpretation of 2D and 3D Seismic Datasets including construction and 3D models fine- tuning;
• Evolution of segmented mature faults – a 3D geometrical fault plane study in order to understand fault evolution (recognition of segments, linkage and overlap zones etc
• Near-fault deformation as potential hydrocarbon reservoirs and their significance in trap integrity assessments, sealing efficiency, and compartmentalization risking predictions.
• Structural validation - geometrical viability of fault planes in areas with complex deformational styles;
• Field structural mapping: basins and highly deformed terrains; cross-section reconstruction and balancing;
• Analyze & interpret geological & geophysical data; • Build & evaluate large and detail, complex computerized geological models
in Gocad & Petrel 3D modeling software; • Integrate seismic, core, engineering, petrophysical and drilling data into
geologic model;
• Experience of well monitoring, real time geological logging, engineering among the various geographical regions allowed me comprehensive and self-confident Wellsite Geological work:
• Had direct responsibility for, the effective management of the mud logging unit, including personnel and equipment; assisted other well site geological personnel and the drilling operation by monitoring and recording drilling parameters, drilling fluid properties and pumping parameters; provided primary well control surveillance by plotting pressure trends; logging information on the rock formations being drilled by describing geological cuttings and monitoring gas shows;
• to analyze, evaluate and describe formations whilst drilling by using cuttings, gas, FEMWD and wireline data; core chips description, pore pressure analyses, picking casing and core points, wireline QA/QC, recognizing unexpected significant drilling breaks, oil fluorescence observations, knowledge of MWD tools such as gamma and resistivity including the knowledge of spatial 3D modeling are valuable assets for geosteering;
• experience of HPHT, horizontal or directionally drilled wells including standard vertical wells.
Geoscientific:
• Landmark/GeoGraphix, Paradigm (Gocad), Petrel 2004 & 2009.2, Reflex, Arc GIS, Tectonics FP, Surfer 8, Geogebra (2-D balancing);
• General: • Operating systems: Windows NT/2000/XP, Windows Vista & Windows 7
(administrator level); • MS Word, Excel, basics of Access, Corel, Power Point AutoCAD, Adobe
Photoshop, Int. Explorer, Fine Reader, etc; • Cartographic expert (drafting): using Adobe Illustrator to draft files from
Arc GIS; • Familiar with databases and basic principles of objective oriented
programming (C++);
• Experienced skills as a team leader and project coordinator; experienced in working in multi-cultural, multi-ethnic teams; comfortable working as a team player in a multi-disciplinary and fast-paced environment;
• Self-starter, fast learner, motivated and dedicated professional with a reputation for quality work and high standards;
• Experience in making presentations, scientific papers & reports in a comprehensive and concise manner;
LANGUAGES (POOR, MEDIUM, GOOD OR FLUENT)
LANGUAGE
WRITTEN
SPOKEN
READ
1
English Fluent Fluent Fluent
2
German Good Fluent Fluent
3
Russian Medium Good Fluent
4 Italian Medium Good Fluent 6 Serbian-Croatian–Bosnian Mother tongue
LIST OF SELECTED SCIENTIFIC PUBLICATIONS AND PRESENTATIONS Spahić, D. Exner, U., Grasemann B. (submitted): Identifying fault segments from 3D fault drag analyis. Journal of Geophysical Research. Spahić, D. Exner, U., Grasemann B. (2010): 3D fault drag characterization: an import tool in a fault description. Geophysical Research Abstracts, Vol. 12, EGU2010-0, 2010. EGU General Assembly 2010. Spahić D., Exner U., Behm M., Grasemann B., Haring A., Pretsch H. (accepted): Listric versus planar normal fault geometry: an example from the Eisenstadt-Sopron Basin (E Austria). International Journal of Earth Science. Spahić D., Exner U., Behm M., Grasemann B., Haring A., Pretsch H. (2010): Heterogeneous distribution of the displacement gradient along normal fault system and possibilities of a model prediction, an example from Eastern Austria (Burgenland). 15th Congress of the Geologists of Serbia. May 2010. Belgrade. Spahic, D. Exner, U., Behm, M., Grasemann, B. & Haring, A. (2009): Chatacterization of shallow normal fault systems in unconsolidated sediments using 3-D ground penetrating radar (SE Vienna Basin, Austria). Geophysical Research Abstracts, Vol. 11, EGU2009-0, 2009. EGU General Assembly 2009. G. Timár, B. Székely, A. Zámolyi, G. Houseman, G. Stuart, B. Grasemann, E. Dombrádi, A. Galsa, D. Spahic, E. Draganits and the ELTE-Leeds-UniWien Workgroup Team (2009): Neotectonic implications by geophysical surveys of topographic features by Airborne laser scanning in the Neusiedlersee/Ferto area (Austria/Hungary). Geophysical Research Abstracts, Vol. 11, EGU2009-0, 2009. EGU General Assembly 2009. Spahic, D. Exner, U., Behm, M. & Grasemann, B. & Haring, A. (2008): Structural 3D modelling using GPR in unconsolidated sediments. International Meeting of Young Researchers in Structural Geology and Tectonics,. Vol.28.Trabajos de Geologia. Oviedo. Spain. Vasić N., K.A.Sherif, Spahić D., Komarnicki S., et.al. (2007): Geological map of Libya in scale 1 : 250.000, sheet Dur At Tálah. Geol.Inst.of Sebia, Belgrade & Int.Res.Cent., Tripoli, Libya. Marović M., Spahić D., Djoković I., Toljić M. Milivojević J. (2006): Extensional unroofing in the area of the Veliki Jastrebac Dome. Annales Géologiques de la Peninsule Balkanique pour l`anne 2007, 68 : 9-20. Marović M., Djoković I., Toljić M. Milivojević J. Spahić D. (2006): Paleogene – Lower Miocene deformations of Bukulja – Venčac crystalline (Vardar Zone, Serbia). Annales Géologiques de la Péninsule Balkanique pour l`anne 2007. 68 : 21-27.
Grants, Awards & Professional Affiliations
Award winner for the best Master Thesis Project in Geology - award title “Milan Milićević geological engineer” Faculty of Mining & Geology, Belgrade, 2006. http://www.rgf.bg.ac.yu/rgfNagrade.html Award of International Research Grants winner – South East Europe Geoscience Foundation, 2006; http://www.see-geoscience.org/news.php AGU, EAGE Member.
E-mail Address E-mail: [email protected] or [email protected]